CERATOPHYLLACEAE (HORN WORT FAMILY) >>89 



precedinc ; st]"o:ma-lol:tes a fourth to a third as lono; as the style ; anthers ahort^ 

 almost sphprirnl : seeds roughened. — Prairies, hid., Wise, and e. Minn. 



4. T. calycinum Engelm. Larger ; petals usually 8-10 ; stamens 30 or more, 

 — Sandy soil or rocks, s. Mo. {Blankinship) to Neb. and southwestw. 



4. PORTULACA [Toura.] L. Purslane 



Calyx 2-cleft ; the tube cohering with the ovary below. Petals 5, rarely 6, 

 inserted on the calyx with the 7-20 stamens, fugacious. Style mostly 8-8- 

 parted. Pod 1-celled, globular, many-seeded, opening transversely, the upper 

 part (with the upper part of the calyx) separating as a lid. — Fleshy annuals, 

 with mostly scattered leaves. (An old Latin name, of unknown meaning.) 



1. P. OLERACEA L. (CoMMON P.) Proj?^r«ie, vcry sm 00th ; leaves ohovate 

 or wedge-form ; flowers sessile (opening only in sunny mornings) ; sepals keeled ; 

 petals pale yellow; stamens 7-12 : style deeply o-6-parted ; flower-bud flat and 

 acute. — Cultivated and waste grounds ; common. — Seemingly indigenous westw. 

 and southwestw. (Nat. from Eu.) 



2. P. neglecta Mackenzie & Bush, known to us from description only, appears 

 to be a more luxuriant plant with ascending stems, larger leaves (2.5-5 cm. 

 long, 1.2-2.5 cm. broad), and more numerous (15-18) stamens. — Rich bottom 

 lands, Mo. and Kan. 



3. P. retusa Engelm. Leaves often retuse ; calyx-lobes obtuse in the bud; 

 petals small or minute ; style shorter, ?j-A-cleft ; seeds larger, sharply tubercu- 

 late ; otherwise like P. oleracea. — Ark. to Tex. and westw. ; reported from 

 Kan., la., and Minn. 



4. P. pil5sa L. Ascending or spreading, copiously hairy in the axils ; leaves 

 line ar-sidnd ate, nearly terete, (>-12 mm. long ; petals red or purple. — Barrens, 

 Mo. and Kan. to Tex., etc. 



CERATOPHYLLACEAE (Hornwort Family) 



Aquatic herbs, with ichorled finely dissected leaves, and mimite axillary and 

 sessile monoecious flowers loithout floral envelopes, but with an S-12-cleft invo- 

 lucre in place of a calyx, the fertile a simple l-celled ovary, with a suspended 

 orthotropous ovule; seed filled by a highly developed embryo ivith a very short 

 radicle, thick oval cotyledons, and a plumule consisting of several nodes and 

 leaves. — Consists only of the genus 



1. CERATOPHYLLUM L. Hornwort 



Sterile flowers of 10-20 stamens, with large sessile anthers. Fruit an achene, 

 beaked with the slender persistent style. — Herbs growing under water ; the 

 sessile leaves cut into thrice-forked thread-like rigid divisions (whence the 

 name from /cfpas, a horn, and ((>vX\ou, leaf). 



1. C. demersum L. Fruit smooth, marginless, beaked with a long persistent 

 style, and with a short spine or tubercle at the base on each side. — Slow streams 

 and ponds, across the continent. (Eu., etc.) Var. echinattm Gray has the 

 fruit mostly larger (6 mm. long), rough-pimpled on the sides, the narrowly 

 winged margin spiny-toothed. — Similar range. 



NYMPHAEACEAE (Water Lily Family) 



Aquatic perennial herbs, with horizontal rootstocks and peltate or sometimes 

 only cordate leaves floating or emersed; the ovules borne on the sides or back 

 (or when solitary hanging from the summit) of the cells, not on the ventral 



