ALISMACEAE. 17 



3-9-ribbed and mostly punctate with dots or lines. 

 Scapes often longer than the leaves. Inflorescence race- 

 mose or paniculate. Flowers perfect, in whorls, each 

 whorl with 3 outer bracts and numerous inner bracteoles. 

 Petals white. Receptacle large, convex or globose. Sta- 

 mens 12-30. Ovaries numerous; style obliquely apical, 

 persistent; stigmas simple. Achenes more or less com- 

 pressed, ribbed and beaked, forming spinose heads. 



1. E. cordifolius (L.) Griseb. Leaves variable, usually broadly 

 ovate, obtuse, cordate at the base, 12-16 cm. long and wide, some- 

 times lanceolate and smaller; petioles angular, striate, 5-15 cm. 

 long; scapes 1 or more, erect 10-30 cm. high; flowers 3-6 in each 

 whorl, on pedicels 6-12 mm. long; bracts linear-lanceolate, acuminate, 

 dilated at the base; inner perianth segments shorter than the outer, 

 4-6 mm. long; stamens usually 12; styles exceeding the ovaries in 

 length; fruiting heads bur-like, 4-6 mm. in diameter; achenes obo- 

 vate or falcate, 6-8-ribbed; beak apical, oblique, 1.5 mm. long. 

 (£. rostratus Engelm.) 



Occasional along streams and banks of ponds. May-July. 



3. LOPHOTOCARPUS Durand. 



Annual aquatic or bog plants with basal long-petioled 

 sagittate or cordate leaves, simple erect scapes bearing 

 flowers in several verticils of 2-3 at the summit, the 

 lower perfect, the upper staminate. Petals white. 

 Sepals distinct, enclosing or enveloping the fruit. Re- 

 ceptacle strongly convex. Stamens 9-15, hypogynous, 

 inserted at the base of the receptacle. Pistillate numer- 

 ous with solitary ovules and an elongated persistent 

 style. Achenes winged or crested; embryo horseshoe- 

 shaped. 



1. L. calycinus (Engelm.) J. G. Smith. Scapes weak, at length 

 decumbent; leaves floating or ascending, entire, hastate or sagittate, 

 the basal lobes spreading, ovate, acute or acuminate, 2-16 cm. long; 

 verticils of flowers 1-5; bracts membranous, orbicular or ovate, 

 or those of the staminate flowers lanceolate; pedicels recurved in 

 fruit; petals 6-8 mm. long; filaments flattened, papillose; achenes 

 obovate, 2 mm. long, narrowly winged on the margins, tipped with a 

 short horizontal triangular beak. ( Sagittaria calycina Engelm.) 



Ballona Creek. 



4. SAGITTARIA L. Arrow-head. 



Perennial aquatic or marsh herbs with tuber-bearing 

 or nodose rootstocks. Leaves with nerves connected by 

 numerous veinlets. Scapes erect, decumbent or floating. 



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