346 1SOCARPHA 



Isocarpha R. Br. Compositae (5). 5 Texas to Peru, W.I. 



IsocMlus R. Br. Orchidaceae (n. 6). 5 trop. Am., W.I. 



Isochoriste Miq. Acanthaceae (iv. B). 2 Java, Angola. 



Isocoma Nutt. (Bigelowia p.p.). Compositae (3). 10 N. Am. 



Isodendrion A. Gray. Violaceae. 3 Hawaiian Is. 



Isodesmia Gardn. Leguminosae (in. 7). 2 Brazil. 



Isoetaceae. Isoetales. Only genus Isoetes (</.v.). 



Isoetales. A class of Pteridophyta. Only fam. Isoetaceae. 



Isoetes L. Isoetaceae. 50 temp, and trop. I. lacustris L. is the 

 quill-wort of Brit, lakes, and /. (chinospora Dur. is also found. Most 

 are aquatics with short stout rhizomes and awl-shaped 1., the habit 

 being like that of Littorella, with which I. is frequently confused. 

 The stem grows in thickness, but very slowly. The 1. spread out at 

 the base and sheath the stem. There are a number of roots, which 

 branch dichotomously. Above the base of each 1., on the inner side, 

 is a large sporangium sunk in the tissue. The outer 1. have micro-, 

 the inner mega-, sporangia, whilst the innermost 1. of all are usu. 

 small and not sporangiferous. The sporangia are imperfectly cham- 

 bered up by strands of tissue (trabeculac] running across them from 

 front to back. The germination of the spores and the development 

 of the embryo resemble the corresponding processes in Selaginella. 



I. is frequently placed with Eusporangiate Filicales (see Campbell, 

 Mosses and Ferns). It differs so much from other Pteridophyta that 

 determination of its relationships is of great difficulty. 



Isoetopsis Turcz. Compositae (7). i temp. Austr. 



Isoglossa Oerst. Acanthaceae (iv. B). 30 Afr., Madag. 



Isolepis R. Br. = Scirpus L. p.p. (Cyper.). 



Isolobus A. DC. = Lobelia L. p.p. (Campan.). 



Isoloma Decne. (Kohleria Regel). Gesneraceae (n). 40 trop. Am. 

 Several sp. form runners above ground, thickly covered with scaly 1. 



Isolona Engl. Anonaceae (5). 15 trop. Afr., Madag. 



Isomeris Nutt. Capparidaceae (v). i Calif. 



Isonandra Wight. Sapotaceae (i). 10 Indomal. Cf. Palaquium. 



Isonema R. Br. Apocynaceae (n. 2). 3 W. Afr. 



Isopetalum Sweet = Pelargonium L'Herit. p.p. (Geran.). 



Isophyllum Hoffm. = Bupleurum Tourn. (Umbell.). 



Isoplexls Lindl. (Digitalis p.p. EP.). Scrophulariaceae (in. i). 2 

 Canaries, Madeira. 



Isopogon R. Br. ex Knight. Proteaceae (i). 30 Austr. 



Isoptera Scheff. ex Burck. Dipterocarpaceae. i Malaya. 



Isopyrum L. Ranunculaceae (2). 20 As., N. Am. 



Isostigma Less. Compositae (5). 10 Brazil, Argentina, on campos. 



Isotoma Lindl. Campanulaceae (in). 8 Austr., W.I., Society Is. 



Isotropis Benth. Leguminosae (in. 2). 10 Austr. 



Ispaghul seed, Planfago ovata Forst. 



Istle, ixtle, Agave. 



Italian millet, Setaria. 



Itatiaia Ule. Melastomaceae (i). i Itatiaia Mt. (near Rio). 



Itea Gronov. ex L. Saxifragaceae (v). 6 E. As., Atl. N. Am. 



Iteadaphne Blume. Lauraceae (n). i Java, Sumatra. 



Itoa Hemsl. Flacourtiaceae (4). i China. 



