Colorado Flora: Eastern Slope, Fourth Edition A Field Guide to the Vascular Plants

Angiosperms

42 ANGIOSPERMS (Monocots and Dicots) ACERACEAE Jussieu 1789. MAPLE FAMILY (ACE) Maples of our area can always be recognized by the combination of three characters: pal­ mately lobed (rarely pinnately compound) leaves, opposite arrangement, and two­winged fruits (samaras). Several genera of the Rosaceae as well as the genus Ribes have “maple leaves” but lack the other features. In Japan there are maples with elm­like leaves, so really the only reliable features, if flowers are lacking, are the opposite leaf arrangement and the samara. The FNA includes this family in the Sapindaceae, based on molecular evidence. 1a. Leaves simple and 3–5­lobed, or sometimes palmately 3­parted; twigs slender, red­ dish, with a narrow pith. Acer 1b. Leaves pinnately compound, with 3–5 leaflets; twigs stout, green or gray, with a thick pith. Negundo ACER L. 1753 [the ancient Latin name]. Maple One species, A. glabrum Torrey, Mountain Maple, 8A. 3­parted leaves (forma trisectum Sargent) are more common in southern counties. In midsummer, leaves develop large, bright red blotches. These are galls containing Eriophyid mites. NEGUNDO Boehmer 1760 [a Malayan name for Vitex negundo, according to E. L. Little]. Box-elder Negundo is so clearly distinct from Acer that we are treating it as a separate genus. One species, N. aceroides Moench subsp. interius (Britton & Shafer) Löve & Löve, 8B. Gulches and streamsides at low elevations. This, the native western race, has the branchlets covered with short hairs, while subsp. violaceus, introduced from the east as a shade tree, has smooth, pale, glaucous twigs. (Acer negundo.) ACORACEAE Martinov 1820. SWEETFLAG FAMILY (ACO) A monotypic family, that is, consisting of a single genus, Acorus. The plants somewhat resem­ ble cattails but the leaves are ensiform, as in Iris. The flowering stem produces a single, densely flowered, finger­like spadix, sessile and at almost right angles to it. The crushed foliage and rhizomes have a very pleasant, sweet fragrance. Until recently the genus was included in the Araceae (aroids). ACORUS L. 1753 [Latin name of some aromatic plant]. Sweetflag One species, Acorus calamus L. [old name for a reed]. Alien, introduced by early set­ tlers for medicinal use. As reported in the FNA, our plants are pollen sterile. Formerly fre­ quent along the meadows of the piedmont valleys but disappearing as wetlands are drained for development. Extinct at Boulder, but still persisting near Fort Collins where it has been protected. ADOXACEAE E. Meyer 1839. ADOXA FAMILY (ADX) A (monotypic) family consisting of a single genus and species. (There is evidence, however, that Sambucus and Viburnum of the Caprifoliaceae belong here.) Adoxa occurs in mountains throughout the Northern Hemisphere. The inflorescence is unique. The terminal flower has a 2­lobed calyx (bracts?) and a 4­lobed greenish corolla, and 4 stamens alternating with the lobes. The filaments are deeply divided, giving the impression of 8 stamens. The lateral flowers (close to the terminal one) have a 3­lobed calyx and a 5­lobed greenish corolla and 5 (looking like 10) stamens. The ovary is half inferior, of 3–4 united carpels. 43 ADOXA L. 1753 [from Greek, adoxos, without glory]. MoSchatel One species, A. moschatellina L., 8D. Moist, often shaded sites, upper montane, sub­ alpine, and alpine. Inconspicuous and growing in such diverse sites as forested streambanks and alpine rockslides. The pale green flowers have a musky odor. With its ternate leaves and umbel­like flower cluster, the plant suggests a small umbellifer. AGAVACEAE Dumortier 1829. AGAVE FAMILY (AGA) Plants of the agave family, along with the cacti, create much of the exotic living landscapes of the American Southwest. These also have been some of the most useful plants for Native Americans, giving fiber for sandals and baskets, food from the seeds, and fermented drinks such as pulque and tequila from the sap. Our only genus, Yucca, is of consuming biological interest because it illustrates the phenomenon of symbiosis. Yucca is visited by a night­flying pronuba moth, Tegeticula yuccasella. Alighting on the flower, the moth first stabs the ovary and lays an egg inside. Then it mounts a stamen and collects a mass of pollen from the anther. It is not possible to pollinate Yucca by merely brushing the stigma with pollen accidentally, for the stigmatic surface is deeply seated in the bottom of the funnel­shaped style. As if understanding the problem, the moth proceeds to stuff the wad of pollen deep in the funnel, thus assuring pollination and, consequently, ample food for the developing larva inside. Pollination results...