keys to the vascular plants of east texas - Botanical Research ...

1108 PONTEDERIACEAE/HETERANTHERA
HETERANTHERA Ruíz & Pav. MUD-PLANTAIN
Annual or perennial herbs submersed or rooted in mud; leaves linear, ribbon- or grass-like,
without a distinct blade, or with ovate to elliptic or elliptic-lanceolate blade; flowers solitary (in
East TX species), from a spathe; perianth � radially symmetrical, salverform; fruit a manyseeded
capsule.
AA genus of 12 species (Horn 2002) of tropical and warm areas of Africa and the Americas n
to North America. (Greek: hetera, different, and anthera, anther, from the dissimilar anthers of
the first described species)
REFERENCES: Horn 1985, 1988.
1. Leaves all sessile, linear, grass-like, pellucid (= � clear, almost transparent); flowers pale yellow;
plants usually completely submersed except for flowers (can become emersed if water levels
drop); spathes sessile in axils of leaves ___________________________________________________ H. dubia
1. Leaves (at least some) petiolate, with an expanded, oblong to ovate, thickish blade; flowers light
blue to purplish blue to white; plants rooted in mud, the leaves forming emersed rosettes or the
leaves floating at the water surface; spathes peduncled ____________________________________ H. limosa
Heteranthera dubia (Jacq.) MacMill., (dubious), GRASS-LEAF MUD-PLANTAIN, WATER STAR-GRASS.
Perennial; petiolate leaves absent; flowers usually exposed at or above the water surface; stamens
all alike; anthers coiled with age. Small streams, quiet waters, and ditches, growing most
extensively in alkaline waters (Moyle 1945; Horn 2002); Comal, Travis (BRIT), Brazos (TAMU),
Bastrop (TEX), Dallas, and Liberty (Turner et al. 2003) cos.; scattered in TX, but mainly c and s
parts of the state; nearly throughout the U.S. and se Canada. Apr–Jun. Flowers are reported to open
within 2 hours after dawn and to wilt by dusk (Horn 2002). [H. liebmannii (Buchneau) Shinners]
Heteranthera limosa (Sw.) Willd., (of muddy places), BLUE MUD-PLANTAIN. Annual 6–25 cm tall,
tufted, becoming rhizomatous; both sessile and petiolate leaves present; sessile leaves forming a
basal rosette; petiolate leaves with petioles 2–12 cm long; flowering stem with a terminal
sheathing spathe; perianth light blue to purplish blue to white, with 3 of the lobes yellow at
base; stamens dimorphic, 2 with short yellow anthers, the third with an elongate, light blue or
yellow anther; anthers not coiled. Shallow water or wet places, including pond margins and
ditches; scattered throughout much of TX but often inconspicuous and rarely collected; widespread
in the c U.S. from KY and TN w to SD and AZ, also CA and FL. Jun–Oct. Flowers are reported
to open within 1 hour after dawn and to wilt by midday (Horn 2002).
Heteranthera rotundifolia (Kunth) Griseb., (round-leaved), ROUND-LEAF MUD-PLANTAIN, is
known from w TX and, according to C. Horn (pers. comm.), could possibly be found in the very
w part of East TX. Horn (2002) distinguished this species from the similar H. limosa as follows:
1. Vegetative stems commonly elongating unless plant emersed from early age; petiolate leaf blade
round to oblong, base cordate to truncate; distal central perianth limb lobe with lateral flanges
_____________________________________________________________________________ H. rotundifolia
1. Vegetative stems elongating only on plants in over 5 cm of water; petiolate leaf blade oblong to
ovate, base truncate to cuneate; distal central perianth limb lobe without lateral flanges __________ H. limosa
PONTEDERIA L. PICKEREL-WEED
AA New World genus of 6 species (Cook 1998b; Horn 2002) occurring from Canada to Argentina.
(Named for Guilio Pontedera, 1688–1757, Italian botanist and professor at Padua)
REFERENCES: Fernald 1925; Ornduff 1966; Lowden 1973; Price & Barrett 1982; Horn 1987; Horn
& Haynes 1987.
Pontederia cordata L., (cordate, heart-shaped), PICKEREL-WEED, WAMPEE. Emergent perennial
rooted in mud, 40–80(–120) cm tall, from thick, short-rhizomatous base; leaves both sessile and