Family 1. ELODEACEAE 
By PER AXEL RYDBERG 
Submerged or floating water-plants, perennial, with rootstocks or stolons, 
sometimes acaulescent. Leaves opposite, whorled, or fascicled. Plants monoe- 
cious, dioecious, or polygamous. Flowers enclosed in a spathe, of 1-3, usually 
more or less united, bracts. Hypanthium in the pistillate flowers well devel- 
oped, usually tubular, in the staminate flowers often short or obsclete. Perianth 
regular or nearly so. Sepals 3. Petals 3, often rudimentary, or wanting. 
Androecium of 3-12 stamens. Filaments short or none, sometimes mona- 
delphous. Gynoecium of a single compound pistil. Ovary 1-celled with 2-5, 
usually 3, parietal placentae. Ovules usually numerous, orthotropous or ana- 
tropous. Fruit indehiscent, maturing under water. Seeds with a straight 
embryo, without endosperm. 
Staminate flowers with 1-3 stamens; plants with horizontal rootstocks. 
Leaves opposite, on short: erect lateral branches, more or less petioled, with broad blades ; 
stigmas filiform ; pollen filiform ; marine plants. 1, HALOPHILA. 
Leaves spiral, but in a basal cluster, linear, without petioles; stigmas short 
and broad ; pollen spheroid; fresh-water plant, almost stemless. 2. VALLISNERIA. 
Staminate flowers with 9 stamens; fresh-water plants, with floating stems and 
whorled leaves. 3. PHILOTRIA. 
1. HALOPHILA Thouars (Gen. Nov. Madag 2; hyponym. 1806); 
Gaud. Voy. Freyc. Bot. 429. 1829. 
Barkania Ehrenb. & Hempr.; Ehrenb. Abh. Akad. Berlin 1832: 429. 1834. 
Small marine monoecious or dioecious plants with horizontal creeping scaly stems or 
rhizomes, routing at the nodes, and with short erect branches. Scales and leaves in pairs, 
opposite, the latter in our species 3-ribbed. Flowers solitary or two enclosed in a 2-leaved 
sheath. Staminate flowers peduncled ; sepals 3; anthers 3, sessile, erect, 2- or 4-celied, 
extrorse; pollen filiform. Pistillate flowers sessile; hypanthium flask-shaped with a slender 
neck ; sepals 3, minute; styles 3, filiform, sessile, channeled and with usually two rows of 
papillae. Fruit membranous, with 3 parietal placentae; seeds many, in 2 rows, anatropous, 
ascending ; cotyledon spirally twisted. 
Type species, Caulinia ovalis R. Br. 
Erect shoots with only one pair of leaves and no scales ; leaf-blades minutely denticulate, almost 
entire-margined. : 1. H. Batllonis. 
Erect shoots with a pair of scales at the middle and 2 or 3 pairs of sub-ver- 
ticillate leaves at the apex ; leaf-blades spinulose-serrulate. : 
Leaf-blades distinctly petioled, obtuse, with 3-5 pairs of transverse veins ; 
petioles 3-5 mm. long. . . 2. Hl. Acshersonit, 
Leaf-blades subsessile or very short-petioled, acute, with 6-8 transverse : 
veins; petioles less than 2 mm. long. 3. H. Engelmannt. 
1. Halophila Baillonis Aschers. Jour. Linn. Soc. 14: 317. 1874. 
The horizontal stem or rhizome slender, filiform, its internodes 1-5 cm. long; scales 
two and two at the nodes, the lower horizontal, embracing the stem, the upper erect and 
enclosing the upright branches, obovate or cuneate, pubescent, hyaline; erect branches 
very short, 1-3 mm. long, bearing 2 leaves and sometimes a secondary horizontal stem ; 
leaves slender-petioled; petioles 5-10 mm. long; blades very thin, hispidulous on both 
sides, oblong or elliptic, 1-3 cm. iong, 3-8 mm. wide, acute at the base, obtuse at the apex, 
with a prominent midrib, two fainter lateral ribs, and about 6 pairs of transverse veins ; 
flower-clusters usually of one lateral pistillate flower and one terminal staminate one in the 
axils of the leaves; bracts hyaline, ovate; staminate flower pedicelled; sepals 3, oval, 
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