ABACK A K (AHUM FAMILY) 257 



ARACEAE (ARUM FAMILY) 



Plants with acrid or pungent juice, simple or compound often veiny leaves, 

 and flowers crowded on a spadix, which is usually surrounded by a spathe. 

 Floral envelopes none, or of 4-6 sepals. Fruit usually a berry. Seeds with 

 fleshy albumen, or none, but filled with the large fleshy embryo. A large family, 

 chiefly tropical. Herbage abounding in slender rhaphides. The genuine 

 Araceae have no floral envelopes, and are almost all monoecious or dioecious ; 

 but the genera of the third and fourth sections, with more highly developed 

 flowers, are not to be separated. 



* Spadix elongated, enveloped in a spathe ; flowers destitute of perianth., monoecious or dioecious. 



1. Arisaema. Flowers covering only the base of the spadix. Leaves not sagittate. 



2. Peltandra. Flowers covering the spadix. Leaves sagittate. 



* * Spadix short-cylindric, subtended by an open spreading petaloid spathe ; flowers (at least the 



lower ones) perfect, without perianth. 

 8. Calla. Flowers covering the whole spadix. 



* * * Spadix globose, enveloped in a very fleshy ovoid spathe ; flowers perfect and perianth present. 



4. Symplocarpus. Sepals 4, hooded. 



* * * * Spadix cylindrical without obvious spathe ; flowers perfect, perianth present. 



5. Orontium. Spadix narrow, naked, terminating the terete scape. 



6. Acorus. Spadix cylindrical, borne on the side of a leaf-like scape. 



1. ARISAEMA Martius. INDIAN TURNIP. DRAGON ARUM 



Spathe convolute below and mostly arched above. Flowers monoecious or 

 by abortion dioecious. Sterile flowers above the fertile, each of a cluster of 

 almost sessile 2-4-celled anthers, opening by pores or chinks at the top. Fertile 

 flowers a 1-celled ovary containing 5 or 6 erect orthotropous ovules; in fruit a 

 1-f ew-seeded scarlet berry. Low perennial herbs, with a tuberous rootstock 

 or corm, sending up a simple scape sheathed with the petioles of the simple or 

 compound veiny leaves. (Name from d/o/s, a kind of arum, and af/xa, blood, from 

 the spotted leaves of some species.) 



1. A. triphyllum (L.) Schott. (INDIAN TURNIP, JACK-IN-THE-PULPIT.) 

 Leaves mostly 2, divided into 3 elliptical-ovate pointed leaflets ; spadix mostly 

 dioecious, subcylindric or club-shaped, obtuse, much shorter than the spathe, 

 which is smooth or corrugated in its tubular part and incurved-hooded at its flat 

 ovate-lanceolate pointed summit. (A. pusillum Nash ; A . Stewardsonii Britton. ) 

 Rich woods. May. Corm turnip-shaped, wrinkled, farinaceous, with an 

 intensely acrid juice ; spathe with the petioles and sheaths pale green, or often 

 dark purple or variegated with dark purple and whitish stripes or spots. 



2. A. Drac6ntium (L.) Schott. (GREEN DRAGON, DRAGON ROOT.) Leaf 

 usually solitary, pedately divided into 7-11 oblong-lanceolate pointed leaflets; 

 spadix often androgynous, tapering to a long and slender point beyond the 

 oblong and convolute-pointed greenish spathe. Low grounds, w. N. E. to Fla., 

 w. to Ont., Minn., e. Kan., and Tex. June. Corms clustered ; petiole 3-6 dm. 

 long, much exceeding the peduncle. 



2. PELTANDRA Raf. ARROW ARUM 



Spathe elongated, convolute throughout or with a dilated blade above. 

 Flowers thickly covering the long and tapering spadix throughout (or only its 

 apex naked). Anther-masses sessile, naked, covering all the uppe:' part of the 

 spadix, each of 4-6 pairs of cells embedded in the margin of a thick and shield- 

 shaped connective, opening by terminal pores. Ovaries at the base of the 

 spadix, each surrounded by 4-5 distinct, scale-like white staminodia, 1-celled, 

 bearing 1-few amphitropous ovules at the base. Berries in an ovoid fleshy 



GRAY'S MANUAL 17 



