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

464 ARACEAE/ARISAEMA
1. Plants free-floating aquatics; leaves 3–15 cm long, velvety hairy, sessile; spathes ca. 15 mm long;
pistillate flower solitary at base of inflorescence ______________________________________________ Pistia
1. Plants rooted in soil (even when in water); leaves often much longer than 15 cm, not velvety
hairy, usually petioled (sessile in Acorus); spathes much longer than 15 mm (apparently absent in
Orontium); pistillate or perfect flowers several to many per inflorescence.
2. Leaves compound with 3–15(–21) leaflets ____________________________________________ Arisaema
2. Leaves simple.
3. Leaves sessile, the blades narrow (0.5–2.5 cm wide), broadly grass-like and parallel-veined;
spadix diverging laterally from an elongate leaf-like structure _______________ Acorus (see Acoraceae)
3. Leaves petioled, the blades broad (usually much greater than 2.5 cm wide—sometimes
less in Cryptocoryne), not at all grass-like, either parallel-veined or net-veined; spadix subtended
by or enclosed by a spathe OR spadix terminal.
4. Leaf blades relatively small, 3–9(–15) cm long, (1–)1.5–3.5(–4) cm wide, usually with
brownish, reddish, or purplish coloration at least on the veins, neither bluish green nor
with a velvety sheen; introduced aquatic known in East TX only from the San Marcos
River in Hays Co. at the extreme w margin of the area __________________________ Cryptocoryne
4. Leaf blades usually relatively large, 6–90 cm long, 3–ca. 90 cm wide, with various coloration,
but if at the small end of this size range then bluish green with velvety sheen;
including species widespread in East TX.
5. Spathe apparently absent (spathe very small at insertion of peduncle to rhizome);
leaf blades cuneate (= wedge-shaped) at base, not at all cordate, sagittate, nor hastate ___ Orontium
5. Spathe well-formed, subtending or enclosing the spadix; leaf blades either cordate,
sagittate, or hastate at base.
6. Leaf blades peltate (the notch at base of blade not as deep as attachment of petiole),
usually with a red or purplish spot on the upper surface distal to where the
petiole attaches to the blade; spathes yellow to orange ________________________ Colocasia
6. Leaf blades not peltate, without a purplish spot; spathes cream white to peach OR
green with pale to white or yellow-green margins.
7. Plants with a tuberous corm at base and with well-developed, horizontal, elongate
rhizomes; spathes cream white to peach; leaf blades (larger ones) to 120
cm long and 90 cm wide; longer petioles 1.8–2 m long; introduced species ___ Xanthosoma
7. Plants with only thick fibrous roots, without a tuberous corm or horizontal rhizomes;
spathes green with pale to white or yellow-green margins; leaf blades
to only ca. 50(–59) cm long and 15(–30 cm) wide; longer petioles to only ca.
0.6(–1) m long; native species ___________________________________________ Peltandra
ARISAEMA Mart. JACK-IN-THE-PULPIT, GREEN-DRAGON
Herbaceous, monoecious or dioecious perennials from a corm; leaves 1–2(–3), with sheathing
bases and 3–15(–21) leaflets, � net-veined; inflorescence a spadix at the end of a scape; scape
usually shorter than petioles; spathe sheath-like or with a tube and limb; spadix long-exserted
or included, the distal portion not flower-bearing; flowers without perianth; staminate flowers
above the pistillate on the spadix or staminate and pistillate flowers on different plants; fruits
1–few-seeded, red or orangish red berries, 10–13 mm in diam.
AA genus of ca. 170 species (Thompson 2000b) of e Africa, Arabia, tropical and e Asia, and
North America. � All parts of Arisaema plants contain microscopic crystals of calcium oxalate
(and possibly also toxins), which if eaten are reported to disrupt cells and cause extreme
burning and swelling of the mouth and throat (Stephens 1980; Cheatham & Johnston 1995).
Native Americans used the properly prepared (cooked, dried, etc.) ground corms of both East
TX species as flour (Yatskievych 1999). Individuals of Arisaema species demonstrate significant
morphological variability (e.g., some plants are many times larger than others); the result