AROIDEA. 417 
Order CLIV. AROIDE. 
Aroidee, Benth. et Hook. Gen. Plant. iii. p. 955. 
Ninety-eight genera are retained by Bentham and Hooker, and the number of 
described species is nearly nine hundred. They are most numerous and generally 
spread in tropical countries and altogether absent from the colder regions. 
1. PISTIA. 
Pistia, Linn. Fl. Zeyl. p. 152, et Gen. Plant. n. 1023; Benth. et Hook. Gen. Plant. iii. p. 964. 
An aquatic monotype. 
1. Pistia stratiotes, Linn. Fl. Zeyl. p. 152; Engler in Mart. Fl. Bras., Arace, 
p. 214, et in DC. Monogr. Phanerog. ii. p. 634. 
y. obcordata, Engler in Mart. Fl. Bras., Aracem, p. 214, et in DC. Monogr. 
Phanerog. ii. p. 634; Hook. Bot. Mag. t. 4564 (species), icon in Flore des Serres, 
t. 625 repetita. 
Pistia occidentahs, Blume, Rumphia, i. p. 79; Liebm. Om Mexicos Aroideer, p. 3. 
Pistia spathulata, Michx.; Liebm. 1. c. 
Aptospermum obcordatum, Klotzsch in Abhandl. K. Akad. Wiss. Berl. 1858, reprint, p. 23. 
Pistia texensis, Klotzsch in Abhandl. K. Akad. Wiss. Berlin, 1852, reprint, p. 28, tt. 1-3. | 
Pistia schleideniana, Klotzsch, 1. c. 
Limnonesis commutata et L. friedrichsthaliana, Klotzsch in Abhandl. K. Akad. Wiss. Berl. 1853, 
reprint, p. 24. 
South Mexico, near Estero (Schiede & Deppe), San Blas to Tepic (Sinclair), valley 
of Mexico (Schaffner); Nicaragua, neighbourhood of Granada (Lévy, 90); Panama, 
(Seemann).—Generally dispersed in Tropican and SvusrropicaL RuxGions, except 
Australia. Hb. Kew. 
The varieties are connected by intermediate forms, and Engler states that some of 
the Mexican specimens are intermediate between his (. spathulata, Michx. (species), 
and his y. obcordata. 
2. ARISAEMA. 
Arisema, Mart. in Flora, 1831, ii. p. 459; Benth. et Hook. Gen. Plant. iii. p- 965. 
There are about fifty described species, the majority of them inhabiting subtropical 
and temperate Asia, a few North America, and one Abyssinia. 
1. Arisema dracontium, Schott, Meletem. i. p. 17, et Prodr. Aroid. p. 39; 
Chapm. Fl. Southern U. S. p. 440; Engler in DC. Monogr. Phanerog. ii. p. 547. 
Arum dracontium, Linn. Sp. Pl. ed. 1, p. 964, ed. 2, p. 1868; Bot. Reg. t. 668. 
PENNSYLVANIA and Kentucky southward to Groraia and Texas.—Nortn Mexico, 
region of San Luis Potosi, 6000 to 8000 feet (Parry & Palmer). Hb. Kew. 
There is a little doubt about the Mexican plant being the same species. 
BIOL, CENTR.-AMER., Bot. Vol. III., February 1885. 3h 
