Aquatic and Wetland Plants of Northeastern North America, Volume II: A Revised and Enlarged Edition of Norman C. Fassett's A Manual of Aquatic Plants, Volume II: Angiosperms: Monocotyledons

Subclass Liliidae: Pontederiaceae / Pickerel-weed Family

Subclass Liliidae Pontederiaceae / Pickerel-weed Family REFERENCES: Hellquist and Crow. 1982; Rosatti. 1987. 1. Plants free-floating; leaves with blades subcircular to broadly elliptic. base widely cuncatc. petioles usually inflated (fig. 580a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1. EichllOrnia 1. Plants rooted. emersed or submersed; leaves with blades ovate to lanceolate (figs. 581. 582) or reniform (fig. 584c). base cordate (fig. 582c) to truncate (fig. 582e.f). petioles not inflated. or leaves linear and ribbon-like (fig. 583a.b). 2. Stamens 6; flowers 2-lipped. in a dense spike-like inflorescence. blue-violet; leaves cordate. hastate. or narrowly to broadly lanceolate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Pontederia 2. Stamens 3; flowers regular. solitary. yellow. blue. or rarely white; leaves reniform. lanceolate. or linear and ribbon-like. 3. Leaves lax. long-linear. ribbon-like. sessile (fig. 583a.b). usually submersed; flowers yellow .................. 3. Zosterella 3. Leaves erect. reniform to rcniform-cordate. or ovate to elliptic to elliptic-Ianceolate. petiolate. usually emersed; flowers white to purplish-blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Heteranthera 1. Eichhornia (Water-hyacinth) Perennial and annual herbs; leaves subcircular. ovate to broadly elliptiC. petioles often inflated; inflorescence spike-like; flowers violetblue with yellow streaks. subtended by a spathe-like bract; fruit a capsule. REFERENCE: Penfound and Earle. 1948. 1. E. crassipes (Mart.) Solms Water-hyacinth Fig. 580 Ponds. canals. rivers. and ditches. Se. Va. s. to Fla.. w. to Mo. and Tex.; Calif.; Trop. Am. In the southern United States this species is locally abundant and sometimes a troublesome weed. 2. Pontederia (Pickerel-weed) Perennial herbs. arising from creeping rhizomes; leaves basal. erect. long-petioled. usually cordate; flowers violet-blue. in a dense spike subtended by a spathe-like bract; fruit a utricle. crested with 6 toothed ridges. REFERENCE: Lowden. 1973. 1. P. cordata L. Pickerel-weed Figs. 581. 582 Margins of lakes. ponds. and streams. marshes. swamps. and ditches. P.E.I. and N.S. w. to s. Que.. Ont.. Mich.. Wisc.. and Minn.. s. to Fla.. Ala.. Miss.. La.. and Tex.; Cuba. Belize. and S.Am. The seedlings consist of submersed rosettes of linear leaves and often have 1 or 2 petiolate. slightly laneeolate leaves. The range of variability in the leaves of this species is considerable . (P. cordata var. lancifolia (Muhl.) Torr.; P. lanceo/ata Nutt.) 3. Zosterella (Water Star-grass) Perennial or annual herbs; stems elongate. often rooting at nodes; leaves alternate. linear. ribbon-like; flowers yellow. emerging from sheathing leaf bases; fruit a capsule. REFERENCES: Horn. 1983; Thieret. 1971. 312 Fig. 580. Eichhornia crassipes: a. habit; b. leaf with inflated petiole; c. flower; d. flower. longitudinal section; e. ovary, cross-section (Mason). 313 Fig. 581. Pontederia cordata: a. habit; b. flower; c. withering perianth, revolute-coiled, exposing shape of developing ovary (C&C). 314 ,;., f~ e d c Fig. 582. Pontederia cordata: a. habit. submersed form; b. habit. submersed juvenile plant; c-f. leaf variations (NHAES). 315 Fig. 583. Zosterella dubia: a. habit (NHAES); b. portion of filiform growth form (NHAES); c. flower (NHAES); d. habit, terrestrial form (F). 316 Haemodoraceae I Bloodwort Family 317 1. Z. dubia (Jacq.) Small Water Star-grass Fig. 583 Alkaline waters or muddy shores of ponds, lakes, and streams. N.B.. Me., and sw. Que. w. to s. Ont.. Minn., Ida., B.C., and Oreg., s. to Fla., Tex., Ariz., Calif., and Mex. This is often confused with a few of the linear-leaved species of Potamogeton, but the presence of an obscure midvein in Zosterella is distinctive in contrast with the conspicuous midvein in Potamogeton. Plants stranded in the mud or floating in dense mats where the foliage reaches the surface tend to produce conspicuous yellow flowers; c1eistogamous flowers often occur on submersed stems. (Heteranthera dubia (Jacq.) MacM.) 4. Heteranthera (Mud-plantain) Perennial or annual herbs; leaves in a basal rosette; flowers blue or white, emerging from sheathing leaf bases; fruit a capsule. REFERENCE: Horn, 1986. 1. Leaf blades ovate to elliptic or elliptic-lancealate; inflorescence I-flowered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. H. limosa 1. Leaf blades reniform to reniform-cordate; inflorescence 2-16-flowered. 2. Flowers white; inflorescence usually about as long as spathe, upper internode of inflorescence more than 10 mm long; mature leaves wider than long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. H. reniformis 2. Flowers purplish (because ofpurple coloration on upper perianth lobe and purple filaments oflateral stamens); inflorescence more than twice as long as spathe, upper internode of inflorescence less than 10 mm long; mature leaves as long as wide ................................................................................ 3. H. multiflora 1. H. limosa (Sw.) Willd. Fig. 584 Muddy shores...