restricted access 5. Ancient Plant Use in West-Central Chihuahua
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81 5 Ancient Plant Use in West-­ Central Chihuahua Karen R. Adams The Proyecto Arqueológico Chihuahua (PAC) analysis of ancient plant use is based on charred or partly charred plant specimens from 28 archaeological sites, including caves, rancherías, possible field houses, and small hamlets and villages. These specimens are suggestive of both subsistence and nonsubsistence needs. Although the PAC encountered sites that ranged from the Archaic through the Historic periods, the excavations focused on (a) the Viejo period, from AD 800 to 1200 or a bit later; (b) the contempor­ aneous occupation of the Laguna Bustillos Basin, represented by rancherías or hamlets of the La Cruz culture; and (c) the Medio period, from about AD 1200 into the 1400s. The PAC project area extended northwest to the Laguna Babícora (west of the town of Gómez Farías) and southeast to Laguna Busti­ llos (near Cuauhtémoc), primarily in basin and range country (see Chapter 2). Prominent biotic communities include (a) Plains and Great Basin Grasslands (Brown 1982c:115–121) in the lowlands ; (b) Madrean Evergreen Woodland (Brown 1982b:​ 59–65) in the uplands; and (c) small amounts of Rocky Mountain and Madrean Montane Conifer Forest (Pase and Brown 1982:43–48) in the highlands. Table 5.1 lists environmental traits and some plant resources in these biotic communities relevant to human groups. East and north of the study area are large stretches of Semidesert Grassland (Brown 1982d:123–131) and Chihuahuan Desertscrub (Brown 1982a:169– 179), which provide additional plant and animal resources, but acquiring those resources would have required trips of up to 100 km or trade with other groups. The plant remains collected during the PAC excavations had the potential to shed light on a broad range of past human behaviors. These include (a) what plant resources groups were eating and what woody plants provided them with fuel, construction materials, and other daily needs; (b) whether reliance on food or nonfood resources changed through time; (c) the relative dependence on domesticated versus wild plant foods; (d) what environments were utilized and whether these changed through time; and (e) whether plant use varied among contemporaneously occupied sites. Methods The PAC archaeologists collected 230 flotation samples and 787 macrobotanical samples from a diversity of sites and features (Table 5.2). This sample set is one of the largest available for prehistoric Chihuahua.1 These samples generally came from contexts such as fire pits, floors,­middens, and general site fill. The project archaeologists processed sediment samples in water to segregate small or barely visible plant parts such as seeds and small wood fragments. The flotation samples ranged from .25 to 4 liters in original volume, with almost three-­quarters of them (n = 171) a standard 2 liters. Samples were processed Table 5.1. Environmental traits and some useful plant resources in the biotic communities of the PAC study area. Biotic Community Environmental Traits Trees Small Trees and Shrubs Perennials Annuals References Plains and Great Basin Grasslands 1,700–2,300 m amsl; annual precipitation averages 300–460 mm, most falling during the summer growing season; growing season averages 125–200 days Juniper (Juniperus) has invaded historically Saltbush (Atriplex), sagebrush (Artemisia), yucca (Yucca), sumac (Rhus), rabbitbrush (Chrysothamnus), mesquite (Prosopis), oak (Quercus) Cacti (Opuntia,­ E chinocereus,­ M ammillaria), short grasses Beeweed (Cleome), mallow (Sphaeralcea), sunflower (Helianthus) Brown 1982a Madrean Evergreen Woodland 1,400–2,200 m amsl; annual precipitation averages > 400 mm, most falling during the summer growing season; growing season averages up to 195 days Juniper (­ J uniperus),­ p inyon (Pinus­ c embroides), other pines (Pinus) Wide range of­ e ver­ g reen oaks (­ Q uercus), agave (Agave), yucca (Yucca), sumac (Rhus), madrone (Arbutus), manzanita (­ A rctostaphylos) Cacti (Opuntia,­ E chinocereus,­ F erocactus,­ M ammillaria), sedge (Cyperus), grasses Wild mints (Salvia), wild beans (Phaseolus) Brown 1982b Rocky Mountain and Madrean Montane Conifer Forest 2,000–3,000 m amsl; annual precipitation averages 460–760 mm; growing season­ a verages < 120 days Fir (Abies), spruce (Picea), Douglas fir (Pseudotsuga), pines (Pinus), aspen (­ P opulus), juniper (­ J uniperus) Oak (Quercus), sumac (Rhus), currant and gooseberry (Ribes), elderberry (Sambucus) Grasses  Pase and Brown 1982 Table 5.2. Number of flotation and macrobotanical samples by site. Site (Ch-) No. of Flotation Samples No. of Macrobotanical Samples Site Type General Nature of Contexts Sampled Time Period(s) Present 5 9 3 Agricultural terraces Shovel tests Late 6 1 Hamlet? Test unit La Cruz, Ceramic period 11 13 12 Village Looter’s backdirt; test units between mounds Medio 102 2 Hamlet or ranchería Trash deposits La Cruz, early Ceramic period 104 2 4 Hamlet or ranchería Pit house La Cruz (990± 60 BP) 112 22 28 Hamlet or ranchería Roasting pit, structure, trash deposits La Cruz, AD 800–1230 125 16 201 Hamlet or ranchería Shallow pit house, Feature 1 La Cruz, ca. AD 1000–1165  Shallow pit house, Feature 3 La Cruz, ca. AD 890–1150  Plow zone La Cruz, ca. AD 800–1200 141 1 Cave Cave deposits, upper Raspadura drainage Unknown 147 1 Cave Cave deposits Mixed prehispanic and historic 151 10 14 Village (one mound) Above and below floors; trash in rooms Medio 152 2 10 Village Looted room and post hole contents Medio 155 1 Village (one mound) Surface collection, El Zurdo area Medio 156 6 39 Village (small) Picacho arroyo, post hole? contents; floor Medio 159 72 90 Village (large) Looted areas; floor; lower levels; El Zurdo Viejo and Medio 182 2 Possible field house Test unit, El Zurdo outlier Unknown 187 1 Outlier or field house Test in 3-room structure, El Zurdo drainage Unknown, probably Medio 198 1 Village? Shovel tests in large site in dunes, Laguna Bustillos Unknown, probably Medio 202 2 16 Hamlet or ranchería? Human burial, site above Ch-102, Laguna Bustillos Unknown 203 1  Test in site at Las Penitas, Laguna Bustillos Unknown 206 1 1  Test in site in dune field, Laguna Bustillos Unknown 212 13 131 Cave Cave deposits, San Bernabe La Cruz (1230± 50 BP) 218 14 10 Village (small) Structure 1, floor and above, Quevedo Viejo (955± 60 BP) 227 1 Cave Cave deposits, north of Namiquipa Mixed prehispanic and historic 230 1 Village (three mounds) General surface debris, Babícora area Medio 240 22 71 Village (small) Fill in/around Structure 1, Santa Clara drainage Viejo 254 25 132 Village (large) Test units; floors and fire pits of Structures 1, 2, 3, and 4 Viejo 261 2 Hamlet or ranchería Test units, La Avispa in Laguna Bustillos La Cruz? 272 11 Village (small) or hamlet Test units and shovel tests in/around 6 structures Viejo Karen R. Adams 84 into light and heavy fractions. Once dry, each light fraction was sorted through a set of graduated geological screens (4 mm, 2 mm, 1 mm, and .5 mm), and materials of all particle sizes were examined for seeds and other reproduc­ tive parts. The exception was items smaller than .5 mm, which usually are broken pieces from taxa already identified based on larger and more complete specimens. Reproductive parts were segregated and identified, and up to 20 fragments of charred wood were identified when they displayed adequate cross-­ section surfaces for viewing anatomical details. The macro­botanical samples included larger plant specimens seen and collected during ­ excavation. These samples were spread out on clean paper plates and examined for reproductive parts. Subsequently, charred wood fragments were ­ handled in the same manner as flotation samples. All items were examined under a Zeiss binocular microscope at magnifications of 8× to 50× and identified by comparison to the author’s extensive modern collection of plant materials from the U.S. Southwest and northern Mexico (backed by specimens in the University of Arizona Herb­ arium). Results Plant Taxa and Parts At least 30 different plant taxa and their parts were identified in the flotation and macro­ botanical samples (Table 5.3). These include at least four domesticates: maize (Zea mays) cobs, cupules (pockets of cobs that once held two kernels ), and kernels; common beans (Phaseolus vulgaris) and tepary beans (Phaseolus acutifo­ lius); butternut squash (Cucurbita moschata) and pumpkin squash (Cucurbita pepo); and cotton (Gossypium; recovered only as a twine fragment). The remaining plant parts represent wild resources gathered for both subsistence and nonsubsistence needs. Although uncharred plant­specimens were preserved in many samples, they could easily represent either natural seed rain onto archaeological sites or historical activities. All plant parts discussed in this chapter were charred or partly charred, presumably due to ancient human activity. The criteria for identification of taxa and parts can be found in Adams 1994b, 1994c, 1994d, 1997a, 1997b, 2003a, 2003b; Adams and Murray 2004; Kaplan 1956; and Martin and Barkley 1961. Use of the word “type” following most taxonomic identifications indicates that the specimens compare well in anatomical and morphological features to the taxon or taxa named but might also represent other plants that have characteristics within the range of the taxon or taxa cited. This conservative approach acknowledges the similarity in appearance of the parts of various plants, especially for archaeological specimens that have been charred and damaged. For ease of use, this chapter indicates “type” only in Table 5.3, but it is implied throughout the text and tables. The ethnographic record provides a rich source of information on plant use in the Southwest/Northwest (Adams and Fish 2006; Castetter 1935; Castetter and Bell 1942, 1951; Cross­ white 1980, 1981; Curtin 1984; Rea 1997; Russell 1975 [1908]; Standley 1912; Yanovsky 1936). Plants useful to historical groups in the Southwest/Northwest may well have been gathered by prehispanic groups living on the same landscapes. The archaeobotanical record of the U.S. Southwest often supports this assumption (Adams 2002a, 2002b, 2004; Adams and Fish 2006; Adams and Van West 2005; Bohrer 1970, 1971, 1987, 1991, 1992; Gasser and Kwiatkowski 1991a, 1991b; Huckell and Toll 2004). Together, the archaeological and historical records provide a continuous record of use of many of the plants discussed below. Data in the tables are presented in terms of taxon ubiquity (presence), which expresses the number of samples in which a given plant and its parts occur within all samples analyzed from a given site or group of sites. This approach provides insights into the frequency of use of a plant resource in prehistory. Ubiquity is often converted to a percentage to compare patterns between sites or time periods, but caution is required when low sample numbers are involved. Sixty-­ six of the 230 flotation samples yielded no identifiable charred or partly charred plant specimens, as these were too small or degraded to identify on the basis of anatomical or morphological traits. In calculating taxon ubiquity, Table 5.3. Charred and partly charred taxa and parts in all samples. Taxon or Taxa ID Level Common Name Part(s) Condition Arctostaphylos/Arbutus Type Manzanita or madrone Wood Charred Cheno-am (Chenopodium-­ Amaranthus)  Goosefoot or pigweed Seed Charred Cleome Type Beeweed Seed Charred Conifer Type Conifer Cone scale, wood Charred Cucurbita moschata Type Butternut squash Seed, seed fragment Charred Cucurbita pepo Type Pumpkin Seed Charred Cucurbita sp. Type Squash Seed, seed fragment Charred Gossypium Type Cotton Twine fragment Charred Gramineae Type Grass family Caryopsis, floret, stem fragment Charred Juglans Type Walnut Nutshell, nutshell fragment, wood Charred Juniperus Type Juniper Fruit, seed, seed fragment, twig, twig fragment, wood Charred, partly charred Leguminosae Type Legume family Cotyledon fragment, seed (wild) Charred Monocotyledon Type Monocot Cordage, leaf fragment, stem­ fragment and impressions, tissue Charred Opuntia (prickly pear) Type Prickly pear cactus Seed Charred Paniceae Type Panic grass subfamily Caryopsis, lemma, palea Charred Phaseolus Type Domesticated bean Cotyledon, cotyledon fragment, seed Charred Phaseolus acutifolius Type Tepary bean Cotyledon   Phaseolus vulgaris Type Common bean Cotyledon, cotyledon fragment   Phragmites australis Type Reedgrass Stem fragment, stem segment Charred Physalis Type Ground cherry Seed Charred Pinus Type Pine Bark, bark scale, cone scale, needle, needle fascicle, needle fragment, nut, nutmeat, nutshell fragment, wood Charred Pinus cembroides Type Pinyon pine Nutshell Charred Populus/Salix Type Cottonwood or willow Wood Charred Portulaca Type Purslane Seed Charred Prunus Type Chokecherry Wood Charred Pseudotsuga Type Douglas fir Wood Charred Quercus Type Oak Nut, nutshell fragment, wood Charred Salvia Type Chia Seed Charred Scirpus Type Bulrush Achene Charred Unknown Type Bark fragment, disseminule, leaf fragment, nutshell fragment, organic material, resin drops, seed, seed half, seed fragment, stem fragment, stem segment, tissue, tuber, wood Charred Yucca Type Yucca Leaf fragment, tissue Charred Zea mays   Maize, corn Cob, cob fragment, cob segment, cupule, embryo, kernel, kernel fragment, stem fragment, stem segment Charred Table 5.4. Ubiquity and percentage values for four Viejo period sites. Taxon  Part  Ch-218 Ch-240 Ch-254 Ch-272 Total [285] Flot [14] Macr [10] Total [24] Flot [22] Macr [71] Total [93] Flot [25] Macr [132] Total [157] Macr [11] Mesoamerican Cultigens Zea mays Cob fragment, cob segment, cupule, kernel, kernel fragment, stem fragment, stem segment 6 2 8 (33.3%) 16 43 59 (63.4%) 12 83 95 (60.5%) 3 (27.3%) 165 (57.9%) Phaseolus Cotyledon, cotyledon fragment     4 4 (4.3%)  23 23 (14.6%) 1 (9.1%) 28 (9.8%) Cucurbita Seed, seed fragment    1  1 (1.1%)  1 1 (.6%)  2 (.7%) Wild Plant Reproductive Parts            Juniperus Seed, seed fragment 4  4 (16.7%) 12  12 (12.9%) 5  5 (3.2%) 1 (9.1%) 22 (7.7%) Unknown Seed, seed fragment, seed half    3 5 8 (8.6%) 2  2 (1.3%)  10 (3.5%) Pinus cembroides, Pinus Nutshell fragment    2 6 8 (8.6%)     8 (2.8%) Gramineae, Paniceae Caryopsis 1  1 (4.2%) 1  1 (1.1%)     2 (.7%) Salvia Seed       2  2 (1.3%)  2 (.7%) Juglans Nutshell fragment        1 1 (.6%)  1 (.4%) Scirpus Achene       1  1 (.6%)  1 (.4%) Wild Plant Nonreproductive Parts            Quercus Wood  1 1 (4.2%)  56 56 (60.2%)  57 57 (36.3% 3 (27.3%) 117 (41.1%) Juniperus Wood  5 5 (20.8%)  27 27 (29.0%)  73 73 (46.5%) 3 (27.3%) 108 (37.9%) Pinus Bark scale, wood  6 6 (25.0%)  17 17 (18.3%) 4 79 83 (52.9%) 2 (18.2%) 108 (37.9%) Phragmites australis Stem fragment, stem segment 2 1 3 (12.5%) 2  2 (2.2%) 9 34 43 (27.4%)  48 (16.8%) Arctostaphylos/Arbutus Wood     1 1 (1.1%)  24 24 (15.3%)  25 (8.8%) Unknown Stem segment, wood, tissue     2 2 (2.2%)  10 10 (6.4%) 1 (9.1%) 13 (4.6%) Juglans Wood     2 2 (2.2%)  9 9 (5.7%)  11 (3.9%) Gramineae Stem fragment     1 1 (1.1%) 3 3 6 (3.8%)  7 (2.5%) Yucca Leaf fragment, leaf tissue        7 7 (4.5%)  7 (2.5%) Populus/Salix, Salix Wood     3 3 (3.2%)  3 3 (1.9%)  6 (2.1%) Conifer Wood  2 2 (8.3%)     2 2 (1.3%)  4 (1.4%) Monocotyledon Cordage, leaf fragment, tissue     1 1 (1.1%)  1 1 (.6%)  3 (1.1%) Pseudotsuga Wood        3 3 (1.9%)  3 (1.1%) Note: Values are for charred and partly charred taxa and parts in flotation (Flot) and macrobotanical (Macr) samples, with the total number of samples by site in square brackets. Taxa and parts are listed in decreasing order of overall ubiquity within general categories. Ancient Plant Use in West-­ Central Chihuahua 87­ samples that contained no identifiable plant parts are included in the count of total samples analyzed from the sites. Site Records of Plant Use Viejo Period Four Viejo period sites preserved evidence of regional plant use between AD 800 and 1200. Sixty-­ one flotation samples and 224 macro­ botanical samples from the Quevedo site (Ch-­ 218), Ch-­ 240, the Calderón site (Ch-­ 254), and the Santa Rosa site (Ch-­272) offer a well-­documented view of subsistence and nonsubsistence resources provided by plants (Table 5.4). Reliance on agriculture is clearly demonstrated by a wide range of reproductive and nonreproductive maize parts preserved in close to 58 percent of the samples examined. To a lesser extent, common beans and tepary beans were an important component of the diet. Evidence of squash use was also preserved . During this period, pinyon (Pinus cem­ broides, Pinus sp.) nuts and juniper (Juniperus) seeds were gathered more often than any other wild foods. Wild grass (Gramineae) grains (caryopses), chia (Salvia) seeds, walnuts (Jug­ lans), and bulrush (Scirpus) achenes also contributed to the diet. With the exception of chia plants, the wild plant contribution to the diet derived almost exclusively from perennial plants, many of them trees (pinyon, juniper, walnut). Chia was the only weedy annual plant preserved as evidence of food use. Oak (Quercus), juniper, and pine trees regularly provided wood for a range of household needs, among them fuel, construction elements, and raw materials for tools (Table 5.4). These trees are common components of regional upland communities today (Table 5.1). Reedgrass (Phragmites australis) stems were often gathered from mesic (damp) habitats where they grow best and likely served whenever people required long, straight, sturdy even-­ diameter structural elements. Other wood types gathered during the Viejo period, but preserved in fewer than one-­ tenth of the archaeobotanical samples, include manzanita or madrone (Arctostaphylos/Arbutus), walnut, and cottonwood or willow (identified as Populus/Salix or Salix). Grass stems were collected on occasion, likely for construction­layers and a range of other uses such as ­bedding and padding. Yucca (Yucca) leaves contain long, strong fibers that can be made into baskets,­sandals, twine, and rope. The cordage and other evidence described as Monocotyledon likely represents use of yucca or of other plants in the region (for example, Agave). Douglas fir wood, identified only at the Calderón site, required travel into upland canyons or higher elevations. La Cruz Culture Six La Cruz culture sites in the Laguna Bustillos Basin, contemporaneous with Viejo period sites elsewhere, yielded plant materials reflecting both subsistence and nonsubsistence activities. These sites were small rancherías or hamlets occupied by, at most, a few households. La Cruz culture sites are more or less contemporaneous with the Viejo period, about AD 800 to 1200. The known sites are located around the Laguna Bustillos, with perhaps better access to water for pot irrigation and daily domestic needs than other valley drainage locations within the basin. Three La Cruz culture sites (Ch-­ 6, Ch-­ 102, Ch-­ 261), represented by one or two macro­ botanical samples each, provided evidence for use of juniper, pine, and oak wood, plus walnuts as a food source. Flotation and macrobotanical­ samples from more thoroughly sampled sites (Ch-­ 104, Ch-­ 125, Ch-­ 212) reveal that maize and beans were important crops (Table 5.5). No evi­ dence of squash was preserved. The most frequently recovered wild plant foods were tree products (walnuts, juniper seeds and fruit, pinyon nuts, and acorns). Occasional wild legume (Leguminosae) seeds, goosefoot (Chenopodium) or pigweed (Amaranthus) seeds, and grass grains were also identified. Occupants of La Cruz culture sites made regular use of pine, juniper, and oak wood (Table 5.5). Wood from one or more additional but unidentified woody plants was also used. Stems and leaves of Monocotyledons such as yucca (Yucca) or agave (Agave) were utilized on occasion , as was manzanita or madrone wood. All the identified wood resources currently grow in the project area. Table 5.5. Ubiquity and percentage values for four La Cruz culture sites. Taxon Part Site Number Ch-104 Site Number Ch-112 Site Number Ch-125 Site Number Ch-212 Total [417] Flot [2] Macr [4] Total [6] Flot [22] Macr [28] Total [50] Flot [16] Macr [201] Total [217] Flot [13] Macr [131] Total [144] Mesoamerican Cultigens Zea mays Cob fragment, cob segment, cupule, embryo, kernel, kernel fragment 1  1 (16.7%) 6 8 14 (28.0%) 5 36 41 (18.9%) 3 2 5 (3.5%) 61 (14.6%) Phaseolus, Phaseolus vulgaris Cotyledon, cotyledon fragment, seed       1 38 39 (18.0%)    39 (9.8%) Wild Plant Reproductive Parts Juglans Nutshell fragment    1  1 (2.0%)  1 1 (.5%)  10 10 (6.9%) 12 (2.9%) Juniperus Fruit half, seed, seed fragment    1  1 (2.0%) 3 4 7 (3.2%) 1  1 (0.7%) 9 (2.2%) Unknown Nutshell fragment, seed, seed half 1  1 (16.7%)    1 2 3 (1.4%) 1 1 2 (1.4%) 6 (1.4%) Pinus Nutshell fragment        2 2 (1.0%)  2 2 (1.4%) 4 (1.0%) Quercus Cotyledon, nut, nutshell fragment        3 3 (1.4%) 1  1 (0.7%) 4 (1.0%) Leguminosae Cotyledon fragment, seed       2  2 (1.0%)    2 (0.5%) Cheno-am Seed 1  1 (16.7%)    1  1 (0.5%)    2 (0.5%) Gramineae Caryopsis    1  1 (2.0%)       1 (0.2%) Wild Plant Nonreproductive Parts               Pinus Bark scale, wood  3 3 (50.0%)  19 19 (38.0%) 1 74 75 (34.6%) 6 83 89 (61.8%) 186 (44.6%) Quercus Wood  1 1 (16.7%)  8 8 (16.0%) 3 56 59 (27.2%)  92 92 (63.9%) 160 (38.4%) Juniperus Wood     12 12 (24.0%) 1 92 93 (42.9%)  48 48 (33.3%) 153 (36.7%) Unknown Wood     1 1 (2.0%) 1 3 4 (1.8%)  74 74 (51.4%) 79 (18.9%) Monocotyledon Leaf fragment, stem fragment, tissue     3 3 (6.0%)  1 1 (0.5%)    4 (1.0%) Phragmites australis Stem fragment, stem segment    1 1 2 (4.0%) 1 1 2 (1.0%)    4 (1.0%) Conifer Cone scale, wood  1 1 (16.7%)  1 1 (2.0%)     1 1 3 (0.8%) Arctostaphylos/Arbutus Wood     1 1 (2.0%)     2 2 3 (0.8%) Note: Values are for charred and partly charred taxa and parts in flotation (Flot) and macrobotanical (Macr) samples, with the total number of samples by site in square brackets. Taxa and parts are listed in­ d ecreasing order of overall ubiquity within general categories. Ancient Plant Use in West-­ Central Chihuahua 89 Medio Period Six Medio period sites yielded evidence of subsistence and nonsubsistence plant resources. Two small villages sites (Ch-­155 and Ch-­230) are represented by single macrobotanical ­ samples collected from site surfaces, providing evi­ dence for the use of maize (Ch-­230) and pine, oak, and manzanita or madrone wood (Ch-­ 155). Four Medio period sites — ​ La Raspadura (Ch-­ 11), the Buenavista site (Ch-­ 151), the Pig site (Ch-­ 152), and the Picacho site (Ch-­156) — ​were thoroughly sampled. Flotation and macrobotanical ­samples from all suggest reliance on maize: a range of maize parts was preserved in more than 22 percent of the samples examined (Table 5.6). Occasionally kernels became charred during preparation, and the use of leftover maize cobs as a fuel or tinder source is indicated by the preservation of charred cob fragments. Seeds of annual goosefoot and pigweed plants in the Cheno-­ am group and of annual purslane (Portulaca) plants were recovered more often than other wild plant foods, suggesting that weeds in maize fields and other disturbed locations were collected as foods. Medio period groups also occasionally ate walnuts, ground cherry (Physalis) fruit, grass grains, and prickly pear (Opuntia) fruit. Pine, oak, and juniper trees regularly provided fuelwood for cooking and heating and most likely structural elements for construction and tool manufacture (Table 5.6). These species are common in the region’s woodland and ­forest communities (Table 5.1). In addition, manzanita or madrone wood was utilized on occasion.­People sought reedgrass stems from damp locations . Dense chokecherry (Prunus) wood may have been carried in for making tools. El Zurdo, a Site of the Viejo and Medio Periods The village of El Zurdo (Ch-­ 159) was occupied during both the Viejo and Medio periods. Located near the northwest end of the PAC study area, this well-­ sampled site preserved an extensive record of subsistence and nonsubsistence activities (Table 5.7).2 This is the only site with evidence of almost all of the agricultural species recovered during the project. Maize remains were found in more than half of both Medio and Viejo contexts, indicating a strong commitment to farming. The recovery of reproductive cob and kernel parts, along with nonreproductive stem parts, suggests that fields were close enough that whole plants could be carried into the village. Common beans, tepary beans, and pumpkin seeds were recovered from contexts that could not be confidently assigned to either the Viejo or the Medio period. El Zurdo was the only site to preserve evidence of Viejo period cotton, in the form of a piece of twine. This single fragment does not imply that cotton fields were present in the area. Wild plants gathered as food include potential weeds from agricultural fields and other disturbed locations, as well as perennial plants found in local woodlands and uplands (Table 5.7). Ground cherry, goosefoot or pigweed (Cheno-­ ams), and beeweed (Cleome) all prefer disturbed habitats and can produce large numbers of fruit and seeds during and following the summer monsoon. Pinyon and juniper trees provide edible fruit and grass grains are harvested all over the world. Regular use of pine, oak, and juniper wood is indicated (Table 5.7). The range of woody plant parts (bark scale, cone scale, needle, needle fascicle , twig, and wood) carried into the village implies that it was surrounded by woodland, as it is today, for at least part of its occupation. The presence of charred needle fascicles (bundles) indicates at least two species of pine trees (a three-­ needle and a five-­ needle pine) were brought to the village. Several pine species in Chihuahua have either three-­ needle (Pinus engelmanii, P. lumholtzii, P. ponderosa) or five-­needle (P. ayaca­ huite, P. flexilis, P. strobiformis) fascicles (Brown 1982b; Pase and Brown 1982). Other Sites Sites of unknown age or with very small ­samples (or both) are grouped here for discussion. No charred identifiable plant specimens were preserved within (a) a single macrobotanical­ sample from Ch-­ 147 (a cave with mixed prehispanic and historical deposits); (b) two macrobotanical samples from Ch-­ 182 (a possible field Table 5.6. Ubiquity and percentage values for four Medio period sites. Taxon Part Site Number Ch-11 Site Number Ch-151 Site Number Ch-152 Site Number Ch-156 Total [106] Flot [13] Macr [12] Total [25] Flot [10] Macr [14] Total [24] Flot [2] Macr [10] Total [12] Flot [6] Macr [39] Total [45] Mesoamerican Cultigens Zea mays Cob fragment, cob segment,­ k ernel, kernel fragment 5  5 (20.0%) 7 5 12 (50.0%) 2  2 (16.7%) 1 4 5 (11.1%) 24 (22.6%) Wild Plant Reproductive Parts Cheno-am Seed 2  2 (8.0%) 2  2 (8.3%)       4 (3.8%) Portulaca Seed    3  3 (12.5%)       3 (2.8%) Unknown Seed    2  2 (8.3%) 1  1 (4.2%)    3 (2.8%) Juglans Nutshell fragment     2 2 (8.3%)       2 (1.9%) Physalis Seed    2  2 (8.3%)       2 (1.9%) Gramineae Caryopsis    1  1 (4.2%)       1 (1.0%) Opuntia Seed          1  1 (2.2%) 1 (1.0%) Wild Plant Nonreproductive Parts               Pinus Bark scale, wood 8 9 17 (68.0%) 9 11 20 (83.3%)  3 3 (25.0%) 2 30 32 (71.1%) 72 (67.9%) Quercus Wood 8 3 11 (44.0%) 10 1 11 (45.8%)  2 2 (16.7%)  17 17 (37.8%) 41 (38.7%) Juniperus Wood 6 2 8 (32.0%) 8 1 9 (37.5%)  2 2 (16.7%)  15 15 (33.3%) 34 (32.1%) Arctostaphylos/Arbutus Wood 4  4 (16.0%) 1  1 (4.2%)  1 1 (4.2%)  4 4 (8.9%) 10 (9.4%) Unknown Stem fragment, wood 1 5 6 (24.0%)          6 (5.7%) Phragmites australis Stem fragment, stem segment     1 1 (4.2%)  1 1 (4.2%) 1  1 (2.2%) 3 (2.8%) Prunus Wood           1 1 (2.2%) 1 (1.0%) Note: Values are for charred and partly charred taxa and parts in flotation (Flot) and macrobotanical (Macr) samples, with the total number of samples by site in square brackets. Taxa and parts are listed in decreasing order of overall ubiquity within general categories. Ancient Plant Use in West-­ Central Chihuahua 91 house for El Zurdo); (c) one macrobotanical sample from Ch-­ 203 (in the Laguna Bustillos Basin); (d) one flotation sample from Ch-­ 206 (an undated site with a few sherds in a dune field in the Laguna Bustillos Basin); and (d) one macrobotanical sample from Ch-­ 227 (a cave with mixed prehispanic and historical ­deposits). Samples from six additional sites (Table 5.8) contained charred plant materials consistent with the archaeobotanical records preserved in the well-­ sampled and dated sites discussed above. Maize was the most commonly recovered subsistence resource; smaller numbers of wild plant food remains were found. Repeated use of pine, juniper, and oak wood reflects the same preferences seen at Viejo period, La Cruz culture , and Medio period sites. Crops Grown in the Region Maize (Zea mays) Charred specimens of maize cob segments and kernels provide information on types grown. A cob segment is complete around the circumference for a portion of cob length, allowing the number of kernel rows to be determined accurately. Forty-­ five charred, well-­ preserved Table 5.7. Ubiquity and percentage values for well-dated Viejo and Medio period contexts at El Zurdo. Taxon Part Viejo Period Medio Period Flot [17] Macr [9] Total [26] Flot [37] Macr [12] Total [49] Mesoamerican Cultigens Zea mays Cob fragment, cob­segment, cupule, embryo, kernel, kernel fragment, stem segment 11 7 18 (69.2%) 17 9 26 (53.1%) Phaseolus Cotyledon 1   1 (3.4%)       Gossypium Twine fragment 1   1 (3.4%)       Wild Plant Reproductive Parts Juniperus Fruit, seed, seed fragment, seed half 1 2 3 (11.5%)       Unknown Seed, seed fragment 3   3 (11.5%) 3   3 (6.1%) Physalis Seed 4   4 (15.4%)  3   3 (6.1%) Cheno-am Seed 4   4 (15.4%)  3   3 (6.1%) Pinus Nut, nutshell fragment, nutshell, nutmeat 1 1 2 (7.7%) 1   1 (2.0%) Gramineae Caryopsis 1   1 (3.4%) 1   1 (2.0%) Cleome Seed 1   1 (3.4%)       Wild Plant Nonreproductive Parts Pinus Bark scale, cone scale, needle, needle fascicle, wood 14 7 21 (80.8%) 23 8 31 (62.3%) Quercus Twig, wood 12 4 16 (61.5%) 12 7 19 (38.8%) Juniperus Wood 9 4 13 (50.0%) 8 5 13 (26.5%) Arctostaphylos/Arbutus Wood 1   1 (3.4%)       Conifer Wood       1   1 (2.0%) Monocotyledon Stem fragment         1 1 (2.0%) Note: Values are for charred and partly charred taxa and parts in flotation (Flot) and macrobotanical (Macr) samples, with the total number of samples by site in square brackets. Taxa and parts are listed in decreasing order of overall ubiquity­ within general categories. Eighteen samples not confidently assigned to Viejo or Medio were excluded from this table. Table 5.8. Ubiquity and percentage values for six additional sites of unknown age or small sample sizes. Taxon  Part Ch-5 Ch-141 Ch-187 Ch-198 Ch-202 Ch-206 Total [34] Flot [9] Macr [3] Flot [1] Macr [1] Macr [1] Flot [2] Macr [16] Macr [1] Mesoamerican Cultigens Zea mays Cupule, cob fragment 1  1   1 2  5 (14.7%) Unknown Seed  1 1      2 (5.9%) Wild Plant Reproductive Parts Juniperus Seed 1      1  2 (5.9%) Gramineae, Paniceae Floret, palea, lemma   1      1 (2.9%) Pinus Nutshell fragment   1      1 (2.9%) Quercus Nutshell fragment   1      1 (2.9%) Wild Plant Nonreproductive Parts Pinus Needle fragment, wood  1 1 1   12  15 (44.1%) Juniperus Wood  1     11 1 13 (38.2%) Quercus Wood   1  1  6  8 (23.5%) Unknown Bark fragment, leaf fragment, wood   1    1  2 (5.9%) Phragmites australis Stem segment       1  1 (2.9%) Populus/Salix Wood       1  1 (2.9%) Note: Values are for charred and partly charred taxa and parts in flotation (Flot) and macrobotanical (Macr) samples, with the total number of samples by site in square brackets. Taxa and parts are listed in decreasing order of overall ubiquity within general categories. Ancient Plant Use in West-­ Central Chihuahua 93 cob segments from El Zurdo had a mean length of 22 mm (S.D., 8 mm) and a mean diameter of 10 mm (S.D., 2 mm). The segments indicate that the El Zurdo maize ears had an average of 10.2 rows of kernels (S.D., 1.8; range, 8–14 rows). Cupules, small pockets of a cob that once held two kernels, displayed a relatively narrow mean width (4.3 mm; S.D. 1.2 mm). Well-­ preserved charred maize kernels from two sites in the area (Ch-­ 112 and Ch-­ 125) indicate that a flint type of endosperm was common (Table 5.9). Fewer than 50 charred kernels from four sites (Ch-­ 112, Ch-­ 125, the Picacho site, and El Zurdo) were identified as having flour endosperm. Single uncharred maize cob segments from five sites (Ch-­ 147, Ch-­ 212, Ch-­ 227, the Calderón site, the Santa Rosa site) and seven uncharred maize cob segments from El Zurdo are conservatively considered to represent historical intrusions into archaeological deposits and will not be discussed further. Even with descriptive information on charred cob segment and kernel traits, it is difficult to state with certainty which landraces of maize were grown in the past. Numerous traits of maize ears, cobs, and kernels are affected by the environment (Adams et al. 1999). Water availability during the growing season affects cob length, kernel length and width, and, to a lesser extent, cupule width (Adams et al. 1999). Charring generally causes cob shrinkage (Brugge 1965; Stewart and Robertson 1971), while kernel thickness can increase (Goette et al. 1994). One of the most stable cob traits is the number of kernel rows, which is unaffected by charring or available moisture (Adams et al. 1999). With these caveats, the charred maize parts within PAC sites may represent two landraces. Most of the maize evidence compares well to a widespread and variable landrace called Chapa­ lote or Pima-­ Papago, which includes ears with 10 to 16 rows of flint kernels and smaller ears with 12 to 14 rows of pop or flint kernels (Adams 1994a:​ 277). There is also evidence from three sites (Ch-­ 125, the Picacho site, El Zurdo) for a type of flour maize. From AD 500 to 700, ­farmers in the Tularosa Cave region of west-­central New Mexico grew an eight-­ rowed maíz de ocho with easy-­ to-grind flour kernels (Cutler 1952:​ 469; Martin 1952:506). This landrace was likely passed northward from ancient farmers in Chihuahua and Sonora. Beans (Phaseolus vulgaris, P. acutifolius) Charred evidence of two types of domesticated beans was preserved within five PAC sites. Ch-­ 125 yielded 12 whole beans, more than 100 cotyle­ dons (bean halves), and more than 2,000 cotyledon fragments, many in association with broken pottery. The site had been plowed, and the upper portions of these vessels extended into the plow zone, so some breakage was to be expected ; but the beans may have been in one or more pots that burned and shattered. Based on cotyledon and whole bean measurements, most of the charred bean evidence appears to represent common beans (P. vulgaris). Whole beans averaged close to 20 mm long, 11.4 mm wide, Table 5.9. Descriptive data on maize kernels and beans from sites Ch-112 and Ch-125. Taxon Part Ch-112 Ch-125 Length (mm) Width (mm) Thickness (mm) Length (mm) Width (mm) Thickness (mm) Zea mays Kernel mean 9.0 9.2 4.4 8.8 9.8 6.5    S.D. 1.2 1.0 .5 1.2 1.2 1.5 Phaseolus Cotyledon mean       18.0 10.4 4.0    S.D.       2.80 1.60 .90 Phaseolus Whole bean mean       19.70 11.40 8.70    S.D.       1.60 1.20 1.10 Note: Ch-112 data based on 14 kernels of flint type endosperm, all measurable for length, width, and thickness. Ch-125 data based on 19 kernels of flint type endosperm (17 measurable for length, 18 measurable for width and thickness), 125 bean cotyledons, and 11 whole beans. Table 5.10. Percentage and rank order values for charred plant parts.    Viejo Period (n = 311) La Cruz Culture (n = 417) Medio Period (n = 155) % Rank Order % Rank Order % Rank Order Mesoamerican Cultigens Zea mays Cob fragment, cob segment, cupule, embryo, kernel,­ kernel fragment, stem­ fragment, stem segment 58.8 1 14.6 1 32.5 1 Phaseolus, P. vulgaris, P. acutifolius Cotyledon, cotyledon fragment 9.3 2 9.8 2     Cucurbita, C. moschata, C. pepo Seed, seed fragment .6 3         Gossypium Twine   4         Wild Plant Reproductive Parts Juniperus Fruit half, seed, seed fragment 8.0 1 2.2 2     Pinus cembroides, Pinus Nutshell fragment 3.2 2 1.0 3   5 Gramineae, Paniceae Caryopsis 1.0 3   5   4 Salvia Seed .7 3         Juglans Nutshell fragment   4 2.9 1   4 Scirpus Achene   4         Quercus Cotyledon, nut, nutshell­fragment    1.0 3     Leguminosae Cotyledon fragment, seed       4     Physalis Seed         3.2 2 Cheno-am Seed       4 4.5 1 Portulaca Seed         1.9 3 Opuntia Seed           5 Cleome Seed   4         Wild Plant Nonreproductive Parts Quercus Wood 42.8 1 38.4 2 38.7 2 Pinus Bark scale, wood 41.5 2 44.6 1 66.5 1 Juniperus Wood 38.9 3 36.7 3 30.3 3 Phragmites australis Stem fragment, stem segment   4   4   5 Arctostaphylos/Arbutus Wood   5   5   4 Juglans Wood   6         Gramineae Stem fragment   7         Yucca Leaf fragment, leaf tissue   7         Populus/Salix, Salix Wood   8         Conifer Cone scale, wood   9   5     Monocotyledon Cordage, leaf fragment, stem fragment, tissue  10   4     Pseudotsuga Wood   10         Prunus Wood           6 Sources: Tables 5.4–5.7. Note: Data are for charred plant parts in 311 flotation and macrobotanical samples from the Viejo period, 417 samples from La Cruz sites, and 155 samples from the Medio period. Within each general category, a taxon assigned Rank Order 1 has the highest percentage of occurrence of parts. Taxa that occur in the same number of samples have the same rank order. Taxa with Rank Orders 1–3 are shaded. Plant parts from unknown taxa were not included. Ancient Plant Use in West-­ Central Chihuahua 95 and 9 mm thick (Table 5.9). Other archaeological sites with more limited evidence of charred domesticated bean cotyledons and cotyledon fragments include El Zurdo, Ch-­ 240, the Calderón site, and the Santa Rosa site. Five charred cotyledons from Arroyo Test 1 at El Zurdo (Lot 1285) were smaller than usual and had the blocky appearance of a type of domesticated tepary bean (P. acutifolius). Common beans were present in New Mexico in the sixth century BC (Kaplan and Lynch 1999; Wills 1988) and appeared to increase in frequency after the adoption of tempered ceramic vessels suitable for boiling. Tepary beans, possibly domesticated in the Southwest/Northwest (Ford 1985; Nabhan and Felger 1978), have been identified in U.S. Southwest sites dating to the first centuries AD. Squash (Cucurbita moschata, C. pepo) Small numbers of squash seeds were recovered in flotation and macrobotanical samples from four sites, suggesting occasional use. A single charred pumpkin (C. pepo) seed from El Zurdo measured 2 by 1 by .5 cm. A charred Cucurbita sp. seed was recovered from Ch-­ 240. A single uncharred butternut squash (C. moschata) seed was recovered from Ch-­ 212; butternut squash seeds are recognized by their wavy, fringed edges (Cutler and Whitaker 1961:478). For unknown reasons, uncharred squash seeds often preserve in open archaeological sites in the U.S. Southwest , so this specimen can reasonably be associated with the prehispanic occupation of the area. A single charred Cucurbita sp. seed from the Calderón site seemed unusually small (1.1 by .5 by .2 cm) and may represent a wild species. Cucurbits have a long history in the Southwest/ Northwest; direct radiocarbon dates place domesticated pumpkins in the Mogollon Highlands by around 3,000 years ago (Wills 1988) and on the southern Colorado Plateau shortly thereafter (Simmons 1986). Cotton (Gossypium) The only evidence of access to cotton fibers consisted of a fragment of charred two-­ ply S-­ twist twine from El Zurdo (PAC Lot 1288). The lack of cotton seeds, bolls, or evidence of looms suggests that cotton was traded in. In the U.S. Southwest, cotton pollen from archaeological sites suggests the presence of this domesticate in Arizona before AD 1, and charred seeds and uncharred twine have been recovered in Arizona and New Mexico contexts dating to the early centuries AD (Adams and Smith 2009). Discussion The almost 900 archaeobotanical samples reveal patterns of plant use in west-­central Chihuahua in prehispanic times. This substantial sample of fragile archaeological plant specimens may have been influenced by differential preservation, variability in sampling contexts, and unequal sample sizes. Despite these effects, charred and partly charred plant specimens from Viejo period , La Cruz culture, and Medio period sites all indicate that maize was the top-­ ranked subsistence resource through time and throughout the PAC study area (Table 5.10). The pattern holds even when only the systematically acquired flotation samples are considered; among those, maize occurs in 58 percent of the Viejo period samples, in 8 percent of the La Cruz culture samples, and in 47 percent of the Medio period samples. This emphasis on maize agrees with the results of studies of carbon isotope signatures of human bones recovered by the PAC (Hodgetts 1996; Webster 2001; Webster and Katzenberg 2008). Domesticated beans supplemented the diet during the Viejo period and at the contemporaneous La Cruz culture sites but were not recovered from deposits dating unambiguously to the Medio period. Two types of squash were also preserved within Viejo period sites, but not in La Cruz culture or Medio period sites. Based on more than 150 archaeobotanical samples, it appears Medio period farmers may have experienced difficulties growing all the crops previously produced in the region. This suggestion is supported by the percentages of samples preserving maize parts: 58.8 percent for the Viejo period and 32.5 percent for the Medio period (Table 5.10). Patterns of wild plant subsistence resource use appear to have shifted through time (Table 5.10). Viejo period people relied on juniper and pinyon trees for fruit and nuts. The contemporaneous La Cruz culture sites in the Bustillos Karen R. Adams 96 Basin preserved evidence that walnuts, junipers , pines, and oaks all provided subsistence products, along with wild legumes, grasses, and annual goosefoot and pigweed plants. By the Medio period, the goosefoot, pigweed, ground cherry, and purslane weeds of agricultural fields and other disturbed locations were gathered most often, suggesting that persistent farming and fuelwood gathering had significantly opened up the landscape, encouraging large populations of weedy plants. If efforts to grow maize were failing, Medio period farmers may have turned to potherbs and seeds from the weeds in fallow fields. The influence of location on subsistence can be assessed among sites of the same period and between sites in different parts of the project area. As already mentioned, issues of sample size and preservation could affect patterning. During the Viejo period, groups likely experienced differential farming success, as suggested by maize ubiquities ranging from 27.3 percent at the Santa Rosa site to 63.4 percent at Ch-­ 240 (Table 5.4). The use of wild plant foods also appears to have varied during the Viejo period. The contemporary La Cruz culture farmers of the Laguna Bustillos Basin also experienced variable, but generally less success as farmers, expressed by maize ubiquities ranging from 3.5 to 28 percent (Table 5.5). Efforts to supplement their diet with wild plants also met with varying success. During the Medio period, the pattern of variability in subsistence efforts continued. Groups occupying the Buenavista site seemed especially successful as farmers, expressed as the highest relative maize ubiquity for the period (50 percent) and via the preservation of the highest diversity of wild plant foods (n = 6), in contrast to lower (11.1 to 20 percent) maize ubiquity and only single wild plant resources preserved in the other Medio period sites (Table 5.6). Even within a single location, the village of El Zurdo, farmers may have been slightly better off during the Viejo period (69.2 percent maize ubiquity) than during the Medio period (53.1 percent maize ubiquity), although wild plants consistently supplemented their diets through time (Table 5.7). Sectors of the project area display clear variability in subsistence success. El Zurdo, in the northwest part of the project area, yielded the best archaeological record of plant foods. The village persisted because its residents were able to grow maize, two species of beans (common and tepary), and two types of squash (butter­ nut and pumpkin). A small fragment of cotton twine from the site suggests access to nonlocal resources. Wild ground cherry (Physalis) fruit were harvested often for food, as were juniper fruit and Cheno-­ am seeds. The environs of El Zurdo seem to have been prime habitat for raising crops, gathering wild plants, and gaining access to conifer woodland resources. In contrast, the La Cruz culture sites, in the southeastern portion of the project area, display a different subsistence pattern. The area is farmed today, as it apparently was in prehispanic times, and maize was the top-­ ranked food in the La Cruz culture samples; but the presence of maize parts in archaeological contexts was the lowest (14.6 percent) of all site groups discussed here. Because the sample size was the highest for the project (417 samples), bias due to small sample size is not considered a factor in this pattern. Despite being next to a lake that could have provided water for pot irrigation, the shores of Laguna Bustillos do not appear to have been an advantageous location for maize farming. The wild plant foods found in the rancherías were from walnut, juniper, pinyon, and oak trees; walnuts were available along local drainages, but the other foods came from upland locations, suggesting that more effort was needed to acquire them. Ground cherry fruit were also important. Laguna ­ Bustillos may be an area that farming groups occupied primarily during the agricultural season, bringing with them supplemental foodstuffs gathered elsewhere. Cultural preferences cannot be ruled out as a contributing factor to these subsistence differences. In contrast to the variability in subsistence patterns at the PAC sites, geographic and temporal patterns of wood use are similar across the project area (Table 5.10). The top-­ranking woods during the Viejo period were oak, pine, and juniper , and for La Cruz culture and Medio period sites, pine, oak, and juniper. Viejo period groups Ancient Plant Use in West-­ Central Chihuahua 97 also gathered reedgrass stems. The ­samples containing these woody resources are fairly consistent : the presence of oak wood in samples varies from 38.4 to 42.8 percent, for example, and juniper wood varies from 30.3 to 38.9 percent (Table 5.10). There was an increasing reliance on pine wood, however, from 41.5 percent in the Viejo period to 66.5 percent in the Medio period. Perhaps four or more centuries of wood harvesting had shifted the availability of different types of wood. Pine wood provides a fair amount of heat, but resin within the wood causes sparking, a problem for small structures built of flammable materials and also for successful pottery firing. In addition, inherent weaknesses in pine wood make it a poor choice for construction. The fact that eight types of wood (oak, juniper, pine, manzanita or madrone, walnut, cottonwood/ willow or willow, conifer, and Douglas fir) were identified within Viejo period sites, and only five (oak, juniper, pine, manzanita or madrone, and chokecherry) within Medio period sites supports the idea that slight shifts in wood availability and/or preference occurred over time. The seasons of availability of plant parts give some indication of when people occupied or visited landscapes  — ​ except for wood, which can be gathered during any season and stockpiled for much later use (Adams and Bohrer 1998). The only wild plant subsistence resource found during the analysis that produces seeds during the spring is chia (Salvia); the remaining wild and domesticated foods ripen during the summer or fall, many of them spurred by and dependent on summer monsoonal moisture. The requirements of an agriculture calendar  — ​ including springtime field preparation, planting, weeding, and the late summer to fall harvest of ripe maize ears  — ​ imply that individuals would have been in residence from at least mid-­ spring through the fall. The archaeological plant record generally remains mute regarding year-­ round occupation, and other archaeological evidence (including inferences based on ground stone, storage facilities, the nature and extent of middens , quantities of broken ceramic vessels, etc.) must be considered in evaluating seasonal versus year-­round occupation. Summary The archaeological plant record preserved in Viejo period, La Cruz culture, and Medio period sites in west-­central Chihuahua provides insights into prehispanic life there. Charred plant speci­ mens in 230 flotation and 787 macrobotanical samples have been a major source of information on ancient subsistence practices and wood use. Although differences in sample numbers and preservation conditions can influence the archaeological plant record, the sheer size of this sample counterbalances these factors. Between the ninth and fifteenth centuries AD, groups in the region were committed agriculturalists growing maize, two kinds of beans, and two kinds of squash. By the Viejo period, cotton was accessible , probably as an import. The local groups supplemented their diets with wild plant foods from trees (pinyon, juniper, oak, walnut) as well as from weeds growing in agricultural fields and other disturbed locations (goosefoot-­ pigweed, ground cherry, purslane, chia, beeweed). Less often, grasses provided edible grains, along with other foods from wild legumes, prickly pear cacti, and bulrush plants. The native people of the region regularly gathered oak, pine, and juniper wood; less often, they carried wood from manzanita or madrone, walnut, cottonwood or willow, chokecherry, and Douglas fir trees back to their dwellings. Leaves from Monocotyledons, including yucca, were harvested for cordage fiber and other household products. Agricultural efforts varied across the region and through time. Based on the ­ ubiquity of remains, Viejo farmers were the most successful at growing maize (58.5 percent of observed ­ samples), their contemporaries in La Cruz culture sites were the least successful (3.5 to 28 percent), and later Medio farmers were moderately successful (32.5 percent). Among Viejo period farmers, the residents of El Zurdo and Ch-­ 240 appear to have had the most success at growing maize (69.2 and 63.4 percent, respectively), while those at the Santa Rosa site struggled to bring in crops (27.3 percent). Among Medio period ­ farmers, residents of El Zurdo and the Buena­vista site were the most successful at growing maize (53.1 and 50 percent, Karen R. Adams 98­ respectively). ­ However, the Medio period trend of declining agricultural success is also seen at El Zurdo, where maize ubiquity of 69.2 percent for the Viejo period dropped to 53.1 percent for the Medio period. Use of wild plant resources to supplement the diet seems quite variable over time and space. The transition from the Viejo to the Medio period saw a shift away from reliable food products from trees to weedy plants of maize fields and other disturbed habitats. Wood use appears to have been more consistent than plant food use. The inhabitants of all sites in the sample consistently gathered wood from oak, pine, and juniper trees. Numerous additional woody resources were sought by the people of the Viejo period, fewer by their La Cruz culture contemporaries and their descendants of the Medio period. One notable pattern is the increasing use of pine wood from the Viejo to the Medio period; if the hot-­ burning, long-­ lasting wood of oaks and junipers was less available , pitchy pine wood may have filled the void. The prehispanic groups of the region acquired plant resources from valley bottom grasslands , mid-level conifer woodlands, and upland conifer forests. The archaeological plant record suggests at least minor shifts through time in the composition of these biotic communities. The Medio period focus on weedy wild plants suggests that land had become disturbed over time, most likely due to farming and possibly to occasional human-­ caused fires. An increase in the use of pine wood during the Medio period also suggests that the available wood choices had narrowed. Clearing for maize fields and constant pressure on trees to provide fuel, construction elements, and raw materials for tools would have eventually impacted the landscape. By the Medio period, groups may have had less access to juniper trees and more access to pine trees, which offered weaker construction elements and a less-­ preferred high-­sparking, resinous source of fuel. Notes 1. The first large archaeological project in Chihuahua , the Joint Casas Grandes Expedition under the direction of Charles Di Peso (1974; Di Peso et al. 1974), took place before archaeologists routinely collected flotation samples. 2. The Viejo period data in Table 5.7 are based on the following samples: (a) Viejo (Lot Nos. 1288, 2065, 2164, 2203, 2212, and 2213); (b) Viejo? (Lot Nos. 2031, 2040, 2041, 2154, 2156, 3038, and 3365); and (c) Late Viejo? (Lot Nos. 2238, 2271, and 3037). The Medio period data are based on the following samples: Lot Nos. 2056, 2057, 2084, 2086, 2087, 2088, 2114, 2115, 2139, 2145, 2149, 2150, 2151, 2152, 2163, 2165, 2217, 3015, 3016, 3036, 3041, 3056, 3058, 3067, 3076, 3081, 3084, 3125, 3137, 3147, 3148, 3191, 3206, 3302, 3366, and 3374. El Zurdo also yielded 18 flotation samples and 42 macro­ botanical samples that could not be assigned to the Viejo or Medio periods; the additional­ samples contain essentially the same taxa and parts reported here. ...