PODOSTEMACEJE. (RIVER-WEED FAMILY.) 399 



oells confluent. Styles 2, slender: stigmas acute. Capsule 4-angled, 4- 

 celled, with a single suspended anatropous seed in each cell, indehiscent. 

 Embryo straight, in copious fleshy albumeu. lladicle long, superior. 

 Consisting of the single genus 



1. CALLITRICHE, L. WATER-STARWORT. 



1. C. verna, L. Floating leaves spatulate or obovate, crowded, the lower 

 ones distant, linear ; fruit nearly sessile, 2-bracted, keeled on the back. ( C. 

 hetcrophylla, Ell.) Var. TERRESTRIS. Smaller (2' -3' long); stems much 

 branched, creeping on damp earth ; leaves (l"-2"long) all linear. Ditches 

 and shallow water, Florida, and northward. March and April. Stems several, 

 6'- 12' long. Leaves ' long. 



ORDER 118. PODOSTEMACEvE. (RIVER-WEED FAMILY.) 



Moss-like aquatic plants, with minute flowers, from a spathe-like in- 

 volucre, and destitute of floral envelopes. Stamens 5 12: anthers 

 2-celled. Capsule 2 - 3-celled, and pointed by as many persistent styles. 

 Seeds numerous, on a thick central placenta, destitute of albumen. 



1. PODOSTEMON, Michx. RIVER-WEED. 



Spathe 2-leaved. Flowers podicelled. Filaments elongated, borne on one 

 side of the stalk of the ovary, united below, and bearing only a single anther. 

 Styles 2, simple. Capsule ribbed, 2-celled, 2-valved. Seeds imbricated. 

 Submerged aquatic plants, attached to rocks and pebbles by disk-like expan- 

 sions of the stem. Leaves 2-ranked, divided into filiform segments. 



1. P. ceratophyllum, Michx. Leaves rigid, sparingly divided, sheath- 

 ing at the base ; flowers solitary, on slender pedicels ; capsule oval, 8-ribbed. 

 Rocky places in rivers, Georgia, and northward. July. Plant olive-green, 

 1'- 4' long. 



2. P. abrotanoides, Nutt. Leaves much divided, with hair-like seg- 

 ments ; flowers 2 3 together, on short pedicels; capsule oblong, 10-ribbed. 

 Gravelly places in the Chattahoochee River, Nuttall. Plant larger than the 

 last. 



ORDER 119. EUPHORBIACE^. (SPURGE FAMILY.) 



Plants commonly with acrid milky juice, and monoecious or dioecious 

 often petalous flowers. Calyx 2 - 8-lobed, mostly valvate in the bud, 

 sometimes wanting. Stigmas 2 -several, simple or divided. Fruit, of 2 - 

 several (mostly 3) 1 - 2-seeded carpels united around a central axis, sep- 

 arating at maturity, rarely 1-celled or indehiscent. Seeds suspended, 

 anatropous. Embryo in fleshy albumen-. Cotyledons flat. 



