254 UMBELLIFERyE. Hydrocotyle. 



+- +- Fruit somewhat compressed dorsally ; the dorsal ribs rather narrowly winged ; the lateral 

 wings broader, distinct : stylopodium somewhat prominent : seed silicate or concave : tall 

 herbs, with white flowers. 



IS. Ligusticum. Dorsal ribs narrowly winged : oil-tubes several in the intervals, obscure: seed 

 reniform in section. 



19. Selinum. Dorsal wings broader : oil- tubes solitary : seed nearly flat on the face. 



-»-•*-+- Fruit much flattened dorsally. 



++ Lateral wings broad, distinct, the dorsal more or less prominent : seed concave on the face or 



nearly flat. 



20. Angelica. Dorsal wings narrower than the lateral : oil- tubes solitary. Stout herbs, with 



white flowers and naked or nearly naked umbels. 



21. Cymopterus. Dorsal wings as broad as the lateral ones : oil-tubes one to several in the 



intervals. Low perennial herbs ; flowers yellow or white ; involucres present. 



++ ++ Lateral wings coherent till maturity ; dorsal ribs filiform : seed nearly flat on the face. 



22. Peucedanum. Lateral wings thin : oil-tubes as long as the fruit. Involucre none. Low 



perennials ; flowers yellow or wdiite, not radiate. 



23. Heracleum. Lateral wings thin : oil-tubes solitary, clavate, not reaching the base of the 



fruit. Stout pubescent perennials, with white, often radiate flowers. 



24. Ferula. Lateral wings corky, as thick as the fruit : oil-tubes numerous, mostly obscure. 



III. Umbels regularly compound. Secondary ribs most prominent, armed with barbed or 

 hooked prickles : oil-tubes solitary under the wings or ribs, conspicuous. Hispid herbs, 

 with white flowers. 



25. Daucus. Seed flat on the face. Biennial or annual. 



26. Caucalis. Seed furrowed on the face or involute. Annuals. 



1. HYDROCOTYLE, Tourn. Marsh Pennywort. 



Calyx-teeth obsolete. Petals slightly concave, valv'ate. Fruit flattened laterally, 

 suborbieular, acutely margined, and with 2 or 3 more or less prominent nerve-like 

 ribs on each side ; oil-tubes none ; carpels not separating. — Smooth herbaceous 

 perennials, growing in or near water, with slender creeping stems ; leaves orbicular- 

 peltate or reniform, with scale-like stipules ; flowers inconspicuous, appearing 

 through the summer, the umbels simple or proliferous one above the other, on 

 slender peduncles. 



A genus widely dispersed over the globe, of about 70 species, the larger number belonging to 

 the southern hemisphere ; sparingly represented in the United States. 



1. H. prolifera, Kellogg. Leaves peltate, emarginate at base, simply crenate, 

 on petioles 1 to 3 inches long : peduncles about equalling or exceeding the leaves : 

 whorls 1 to 4, about 8-flowered (12-20-flowered, Kellogg), with numerous bractlets, 

 the pedicels a line or two long (3 to 6 lines, Kellogg) : fruit a line broad, slightly 

 emarginate at base ; ribs two on each side, prominent ; commissure narrow. — 

 Proc. 'Calif. Acad. i. 15. 



A slender species, growing about San Francisco and elsewhere, first collected by Chamisso ; 

 collected also by Coulter in " Sonora Alta," and by others in Mexico. It has been referred to 

 H. vulgaris of the Old World, from which it is distinguished by its much longer peduncles and 

 pedicels, the fruit in H. vulgaris being nearly sessile. 



2. H. ranunculoides, Linn. fil. Stouter, usually floating : leaves not peltate, 

 orbicular, with 3 to 7 crenate lobes, on petioles 2 to 9 inches long: peduncles much 

 shorter than the petioles, }, to 3 inches long, reflexed in fruit : flowers 5 to 10 in a 

 capitate umbel : fruit 1 to 1| lines broad, with thickened scarcely angled margins, 

 rather obscurely 3-nerved on each side, longer than the pedicels. 



About San Francisco ; San Diego Co. (Palmer) ; and probably elsewhere. Common also in the 

 Atlantic States, and from Florida westward through Mexico. 



