In wet soil of wooded swamps, open floodplain woods and on lake shores in s.e, 

 Tex. where recently found in Newton Co., Sept. -Oct.; mainly on Coastal Plain 

 from s.e. Va. to s.e. Tex., n.w. in the interior to s. Mo. and s. O. 



Fam. 90. Elatinaceae Dum. Waterwort Family 



Low annual or perennial herbs with opposite simple leaves with membranous 

 paired stipules between them and small regular axillary flowers; the persistent or 

 marcescent sepals and petals imbricated in the bud; stamens as many as the petals 

 and alternate with them or twice as many; ovary 2- to 5-celled, the placentae axile; 

 valves of capsule alternate with dissepiments; seeds several to many, oblong- 

 cylindric, straight or curved, usually with a reticulate surface pattern. 



A family of the following two genera and about 40 species of cosmopolitan 

 distribution. 



1. Plants less than 1 dm. tall or long, creeping, glabrous; flowers 2- to 4-merous; 



sepals obtuse, not scarious-margined 1. Elatine 



1, Plants 1 dm. or more tall, erect-ascending, glandular-puberulent; flowers 5- 



merous; sepals cuspidate, scarious-margined 2. Bergia 



1. Elatine L. Waterwort 



Aquatic, amphibious or terrestrial dwarf annuals from the bottoms of pools or 

 slow streams or on wet sandy or muddy shores; stems erect or prostrate, flaccid- 

 succulent, to about 10 cm. long; herbage glabrous; leaves (in ours) opposite, 

 sessile or petioled, with hyaline entire or toothed stipules, the blade linear-spatulate 

 to oblong or orbicular-obovate, the margin obscurely and remotely crenate; flowers 

 1 or 2 to a node, sessile or pediceled, 2-, 3-, or 4-merous; sepals 3 or 4, or reduced 

 to 2, equal or unequal in size, in some species withering-persistent; petals mem- 

 branous, hypogynous, usually orbicular in outline, in terrestrial plants often campan- 

 ulately spreading, in aquatic plants often closely investing the ovary or in some 

 not evident; stamens as many as the petals or twice as many or (in some aquatic 

 forms) reduced to 1 or sometimes none; styles or capitate stigmas 2 to 4; capsule 

 membranous, 2- to 4-celled, several- to many-seeded, 2- to 4-valved, septicidally 

 dehiscent, the partitions left attached to the axis or evanescent. 



A genus of about 20 species in fresh-water habitats in temperate and warm 

 regions. 



The nomenclature of some of the species is in a state of flux, usually with no two 

 authors in agreement. The genus is in need of a thorough revision. These plants 

 form part of the diet of various ducks. 



As Fassett (p. 250) points out, "The differentiation of species is based almost 

 entirely on mature seeds, which must be examined with a compound microscope. 

 Superficially all species look alike; in fact, members of the same species growing 

 on mud or in water will differ more in appearance than will species growing in the 

 same habitat. In other words, the general form of the plant is greatly influenced by 

 submergence or emergence, only the seeds remaining diagnostic." 



1. Capsule 4-celled; pedicels elongating in fruit; seeds J- or U-shaped; stamens 

 8 1. E. calif ornica. 



1. Capsule 2- or 3-celled, sessile; seeds slightly curved to almost straight; 



stamens 3 or varying from 1 to 6 (2) 



2(1). Seeds with 9 to 15 pits in each longitudinal row, the pits nearly as long 

 as broad; leaves not emarginate at tip 2. E. hrachysperma. 



2. Seeds with 16 to 35 pits in each longitudinal row, the pits much broader than 



long; leaves commonly emarginate at tip (3) 



1142 



