420 roi>osT?:MACE.'E. (kivkrwked family.) 



OKI. IK 117. CALLITKIC'HACK^E. (Wateu-Starwort 

 Family.) 



Siniill aquiitic animals, witli oppo.site entire leaves, and solitary ax- 

 illarv i>olyyaiiious Hdwl'Is witlitnit lluial envelope.s. Stamen mostly 

 solitaiv, *J-biacted in the sterile Hower. Filament slender: anther 

 renilorm, the cells confluent. Styles *J, slender : stigmas acute. Cap- 

 sule 1-angled, -1-celled, with a single suspended anatropous seed in each 

 cell, indehisceiit. Embryo straight, in copious fleshy albumen. Rad- 

 icle long, superior. — Consisting of the single genus 



1. CALLITRICHE, L. Watek-Starwort. 



1. C. heterophylla, rur.>li. Floating leaves spatnlate or ol>ovate. 

 crowded, tlie lower ones distant, linear ; fruit nearly sessile, 2-ljratted, keeled 

 on the liaek. — Var. teuukstkis. .^ Smaller (2'-3' long); stems much 

 brauclied, creeping on damp earth; leaves (r'-2" l<jng) all linear. — 

 Ditclies and shallow water, Florida, and uortliward. March -April. — Stems 

 several, 6'- 12' long. Leaves i' long. 



2. C. peploides, Nutt. Stems creeping ; leaves uniform, obovate or 

 spatnlate ; fruit nearly sessile, circular, notched at the a^jex, tlie sides gil)bous, 

 grooved around the wingless margin, as long as the widely spreading stigmas. 

 — Florida and westward, on damp earth. Feb. - Marcii. 



3. C. Austinii, Engelm. Smaller (r or less long) ; fruit short-pedicelled, 

 flattened, wider than long, notched at both ends, w-ith narrow denticulate 

 wings, longer than the spreading stigmas. — Tennessee (Dr. Gattinger), and 

 nortiiward. April. 



Ordkr 118. PODOSTEMACE^. (Riverweed 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 2-8-celled, pointed by as many persistent styles. 

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



1. PODOSTEMON, Michx. Riverweed. 



Spathe 2-lpaved. Fhjwcrs pedioelled. Filaments elongated, borne on one 

 side of the stalk of the ovary, united I)elow, and bearing only a single anther. 

 Styles 2, simple. Capsule rit.bed, 2-celled, 2-valved. Seeds imbricated. — 

 Submerged acjuatic 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 lia.«e ; flowers solitary, on slender pedicels ; capsule oval, 8-ribbed. — 

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

 l'-4' long. 



