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

ARISAEMA/ARACEAE
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has been disagreement over the taxonomy of the group. The ability of plants to change sexual
expression is well known in the genus (e.g., A. dracontium and A. triphyllum), with changes
correlated with plant size and environmental conditions (e.g., Schaffner 1922; Lovett-Doust &
Cavers 1982a, 1982b; Bierzychudek 1984; Clay 1993; Dieringer & Cabrera R. 2000; Ruhren &
Handel 2000; Richardson & Clay 2001). Smaller individuals are typically staminate, while
larger ones have both staminate and pistillate flowers or pistillate only (Thompson 2000b). In
addition, a change in sexual expression can be induced experimentally by changing the amount
of leaf area or by modifying environmental factors such as soil nutrient levels (Thompson
2000b). The common name JACK-IN-THE-PULPIT is derived from the spadix (= “jack”) being enclosed
in the “pulpit”-like spathe. (Greek: aris, a kind of arum, and haima, blood, from the redspotted
leaves of some species)
REFERENCES: Schaffner 1922; Huttleston 1949, 1981, 1984; Treiber 1980; Lovett-Doust & Cavers
1982a, 1982b; Murata 1990; Clay 1993; Boles et al. 1999 [2000]; Dieringer & Cabrera R. 2000; Richardson
& Clay 2001; Guzman & Guzman 2002; Diggs & O’Kennon 2003.
1. Primary leaf of mature plants divided into (5–)7–15(–21) unequal leaflets (sometimes some of
the divisions not completely separated into leaflets); summit of spathe with inrolled margins;
spadix long-exserted beyond the spathe, tapering to a long slender point; fruit cluster conical
____________________________________________________________________________ A. dracontium
1. Primary leaf of mature plants divided into 3 or 5 leaflets; summit of spathe flat, the margins not
inrolled; spadix included, not exserted beyond the spathe, apically blunt; fruit cluster ovoid or
subglobose ___________________________________________________________________ A. triphyllum
Arisaema dracontium (L.) Schott, (Greek name for a kind of arum, presumably from draco,
dragon), GREEN-DRAGON, DRAGON-ROOT, GREEN-JACK. Leaf usually solitary, divided into (5–)7–
15(–21) unequal and sometimes asymmetrical leaflets (sometimes some of the divisions are not
completely separated into leaflets), these in a � semi-circular arrangement (very young plants
can have the primary or only leaf with only 3 leaflets); spathe sheath-like, the summit with
margins inrolled, tapering to a slender point; spadix 8–15+ cm long, the sterile portion long-exserted;
fruits orangish red. Low woods, moist slopes; Pineywoods and Gulf Prairies and Marshes
w to Cross Timbers and Prairies and e Edwards Plateau; se Canada and throughout e U.S. w to
MN and TX. Late Apr–May. Both diploids (2n = 28) and tetraploids (2n = 56) are known, and reproduction
is reported to occur both clonally (offsets from the corm) and sexually (Boles et al.
1999 [2000]; Yang et al. 1999). The rust fungus Uromyces ari-triphylli (Schwein.) Seeler sometimes
causes conspicuous lesions on GREEN-DRAGON in East TX (J. Hennen, pers. comm.). The
tissues contain injurious calcium oxalate raphides (Lampe & McCann 1985). � m/276
Arisaema triphyllum (L.) Schott, (three-leaved), JACK-IN-THE-PULPIT, INDIAN-TURNIP, INDIAN CHER-
RIES. Leaves 1 or 2, often 2 on flowering individuals, with 3 or 5 leaflets; spathe with a tube and a
limb, the summit arching over the spadix, the margins not inrolled; spadix 3.5–8(–9) cm long,
not exserted; fruits red. Moist to wet woods, moist slopes, swampy areas, and bogs. Mar–May.
Detailed study of these extremely variable plants led Huttleston (1949, 1981, 1984) to conclude
that the variation seen in the JACK-IN-THE-PULPITS was best represented taxonomically by recognizing
a single species with 4 subspecies (2 of which are treated here). He indicated that
“…plants of the four subspecies are very distinctive and readily identified, at least in living condition.
Since many of the key characteristics…are obscured or lost during drying, it is not always
possible to identify herbarium specimens to subspecies.” Treiber (1980) recognized 3 subspecies
(2 in TX) and synonymized the 5-leaved form [subsp. quinatum] with subsp. pusillum
(Peck) Huttl. Because “much overlap occurs in expression of the characteristics supposedly defining
infraspecific taxa,” because numerous intermediate forms exist, and because the ranges of
the subspecies overlap, Thompson (2000b) recently recognized a single variable species without subspecies.
Still more recently, Guzman and Guzman (2002) followed Treiber (1980) in submerging