226 ARACEAE 



Plants normal, with the flowers in a spadix, this sometimes subtended by or partly 



enclosd in a spathe. FAM. 1. ARACEAE. 



Plants reduced to small floating thalloid structures, with one or few flowers. FAM. 2. LEMNACEAE. 



FAMILY 1. ARACEAE Neck. ARUM FAMILY. 



Fleshy, mostly acaulescent herbs, with short or elongated rootstocks. Leaves 

 basal : blades simple, sometimes divided. Flowers perfect, monoecious or dioe- 

 cious, borne in a dense thick spadix, the staminate above the pistillate. Spadix 

 subtended by or enclosed in a spathe. Perianth of 4-6 scale-like members, or 

 wanting. Androecium often of 4-10 stamens. Filaments very short. Anthers 

 2-4-celled,with thick truncate connectives : sacs opening by dorsal slits or pores. 

 Gynoecium of a single carpel or several united carpels. Ovary 1-several-celled. 

 Stigma terminal, minute. Ovules 1-several in each cavity. Fruit a berry or 

 utricle. Seeds with a smooth or sculptured testa. 



Flowers monoecious or dioecious : perianth wanting. 

 Spadix free : pistillate ftowers numerous. 



Leaf-blades 3-many-divided : axis of the spadix naked above. 



Leaf-blades palmately divided : spathe involute below, hooded above : spadix 



included, terete or obscurely angled. 1. ARISAEMA. 



Leaf-blades pedately divided : spathe convolute throughout : spadix exserted, 



more or less flattened or 2-edged. 2. MURICAUDA. 



Leaf-blades simple : axis of the spadix completely covered with flowers. 3. PELTANDRA. 



Spadix adnate to the spathe : pistillate flower solitary. 4. PISTIA. 



Flowers perfect : perianth of several scale-like members. 



Spadix surrounded by a spathe. 5. SPATHYEMA. 



Spadix naked, merely subtended by a spathe. 



Spadix terminating the club-shaped scape. 6. ORONTIUM. 



Spadix borne somewhat laterally on the leaf-like scape. 7. ACORUS. 



1. ARISAEMA Mart. 



Scapose fleshy herbs, with acrid corms. Leaves basal, 1-3, erect : blades palmately 

 3-5-divided. Scapes erect, shorter than the leaves. Spadix free, bearing flowers on the 

 lower part of its markedly differentiated fertile portion, the sterile portion club-shaped, 

 included. Spathe cornucopia-like, convolute below, dilated above. Flowers destitute of a 

 perianth, dioecious or monoecious : staminate of 4 nearly sessile 2-4-celled anthers, each 

 opening by confluent slits at the apex. Pistillate flowers several, each with a 1-celled ovary. 

 Stigmas peltate-capitate. Ovules 1-several, orthotropous. Fruits subglobose, red, in 

 conspicuous heads. Endosperm copious. JACK-IN-THE-PULPIT. INDIAN TURNIP. 



Leaf-segments 3 : spathe acuminate or acute. 



Sterile part of the spadix 1-2 mm. thick : fruits 4-5 mm. in diameter. 1. A. pusillum. 



' Sterile part of the spadix 4-6 mm. thick : fruits 8-12 mm. in diameter. 



Dilated portion of the spathe mainly purple and brown, less than twice as 



long as broad, acute or short-acuminate. 2. A. triphyllum. 



Dilated portion of the spathe green, over twice as long as broad, long-acuminate. 3. A. acuminatum. 

 Leaf-segments 5 (the lateral ones sometimes more or less united): spathe abruptly 



short-pointed. 4. A. quinatum. 



1. Arisaema pusillum (Peck) Nash. Corm small, subglobose or spheroidal: leaves 

 usually 2, or 1 on staminate plants, 2-4 dm. tall ; petioles 5-18 cm. long, or 7-10 cm. in 

 the case of the second leaf ; segments 3, thinnish, ovate to oblong or elliptic, acuminate, 

 5-12 cm. long, green on both sides : scapes shorter than the petioles : spathe with the convo- 

 lute portion 3-5 cm. long, white without, red-brown within, the dilated part 5-6 cm. long, 

 acuminate, green without, dark red-brown within, or almost black : spadix slender, 1-2 

 mm. thick ; staminate 4-5 cm. long ; pistillate 5-6 cm. long : anthers purple : fruits red, 

 1-5 mm. in diameter. 



In open swamps and deep woods, New York to Kentucky and Georgia. Late spring and summer. 



2. Arisaema triphyllum (L.) Torr. Corm globose or spheroidal, sometimes 10 

 cm. in diameter : leaves usually 2, sometimes solitary, 2-16 dm. tall ; segments 3, ovate 

 to elliptic or the middle one obovate, sessile, 8-30 cm. long, acute or acuminate, erose, the 

 lateral ones sometimes lobed at the base : scape erect, shorter than the petioles, simple : 

 spathe with the lower portion Vhite, the dilated portion often striped with purple, or 

 brown and green, acuminate : spadix stout, 4-6 mm. thick ; staminate 4-9 cm. long ; 

 pistillate 5-10 cm. long : fruits bright red, 10-12 mm. in diameter. 



In swamps or on shaded hillsides, Nova Scotia to Minnesota, Kansas, Florida and Louisiana. 

 Spring. 



3. Arisaema acuminatum Small. Similar to A. triphyllum in habit, but much more 

 slender and delicate. Leaves 3-5 dm. tall ; segments lanceolate to elliptic or ovate-lanceo- 



