HYDEOCHABITACEAE. 9 



sessile, extrorse anthers. Pistillate flower sessile, with 3 very small sepals, a 

 1-celled, beaked ovary and a 3-parted style. Fruit enclosed in the spathe. 

 Seeds numerous, the embryo with spirally bent cotyledons. [Greek, salt-loving. J 

 About 7 species of tropical distribution. Type species: Caulinia ovalis B. Br. 



1. Halophila Engelmanni Aschers. in Neumayer, Anleit. Wiss. Beob. 368. 1875. 



Rootstocks buried in sand or mud in water up to 4 m. deep or deeper, 

 branched, the slender stems 3-6 dm. long. Leaves linear-oblong to oblanceolate, 

 mostly whorled at the ends of the branches, short-petioled, 1-3 cm. long, 3-6 

 mm. wide, obtuse or acutish at the apex, narrowed at the base, 3-nerved, finely 

 and sharply serrulate; pistillate flowers axillary, enclosed by 2 lanceolate 

 bracts, the hypanthium flask-shaped, about 8 mm. long, the sepals minute, the 

 3 stigmas filiform, about 3 cm. long; staminate flowers unknown. 



In salt water, often washed ashore, Abaco, North Bimini, Rose Island, Great 

 Exuma : Florida ; Cuba. Halophila. 



Family 2. HYDROCHAEITACEAE Aschers. 



Frog's-bit Family. 



Submerged or floating aquatic herbs, the leaves various. Flowers regu- 

 lar, mostly dioecious, appearing from an involucre or spathe of 1-3 bracts 

 or leaves. Perianth 3-6-parted, the segments either all petaloid or the 3 

 outer ones small and herbaceous, the tube adherent to the ovary at its base 

 in the pistillate flowers. Stamens 3-12, distinct or monadelphous. Anthers 

 2-celled. Ovaiy 6-9-celled. Styles 6-9. with entire or 2-cleft stigmas. 

 Ovules anatropous or orthotropous. Fruit ripening under water, inde- 

 hiscent. Seeds numerous, without endosperm. About 14 genera and 40 

 species of wide distribution in warm and temperate regions. 



1. THALASSIA Banks; Konig & Sims, Ann. Bot. 2: 96. 1805. 



Marine herbs, with elongated rootstocks. Leaves several at a joint, sheath- 

 ing at the base, linear, elongated, the scape arising from the cluster of leaves. 

 Flowers dioecious, solitary in narrow spathes of two bracts, these united into a 

 tube at the base. Staminate flowers long-pedicelled; perianth of 3 petaloid 

 sepals; stamens 6; filaments very short; anthers opening laterally. Pistillate 

 flower nearly sessile in the spathe, caducous; ovary 6-9-celled, beaked. Fruit 

 stalked, rugose or nearly echinate, opening by many valves. Seeds numerous. 

 [Greek, referring to its growth in the ocean.] Two known species, the follow- 

 ing typical. 



1. Thalassia testudinum Konig; Konig & Sims, Ann. Bot. 2: 96. 1805. 



Submersed, glabrous. Eootstocks creeping, elongated; stems short, arising 

 from the nodes of the rootstock; leaves 2-5, sheathing the stem; blades linear, 

 strap-like, 0.5-3 dm. long, obtuse, withering-persistent; scapes solitary, central; 

 fruit globose or oval, echinate-pubescent, pointed. 



In shallow salt water, Andros and New Providence to Watling's Island and 

 Inagua : Bermuda; Florida; throughout the West Indies. Ttjbtle-grass. Catesby, 

 2 : pi. 88. 



2 



