CERATOPHYLLACEAE (HOBNWORT FAMILY) 889 



preceding ; stigma-lobes a fourth to a third as long as the style ; anthers short, 

 almost spherical ; seeds roughened. Prairies, Ind., Wise., and e. Minn. 



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

 Sandy soil or rocks, s. Mo. (Slankinship) to Neb. and south westw. 



4. PORTULACA [Tourn.] 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 3-8- 

 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.) Prostrate, very smooth ; leaves obovate 

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

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

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

 and south westw. (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, 1.2-2.6 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, 3-4-cleft ; seeds larger, sharply tubercu- 

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

 Kan., la., and Minn. 



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

 linear-suhulate, nearly terete, 6-12 mm. long ; petals red or purple. Barrens, 

 Mo. and Kan. to Tex., etc. 



CERATOPBTLLACEAE (HORNWORT FAMILY) 



Aquatic herbs, with whorled finely dissected leaves, and minute axillary and 

 sessile monoecious flowers without floral envelopes, but with an B-l'2-cleft invo- 

 lucre in place of a calyx, the fertile a simple 1-celled ovary, with a suspended 

 orthotropous ovule ; seed filled by a highly developed embryo with 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 tctpas, a horn, and <j>ti\\ov, 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. ECHINATUM 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 



