ON A GRAMA CEM. 477 



capitate and stigmatiferous at the summit. In each of the cells is a 

 descending, anatropous ovule, with micropyle at first interior and 

 superior. 1 The fruit, turbinate, dry, coriaceous, indéhiscent, bears 

 at the summit the scar of the style, and is laterally dilated about the 

 middle of its height, into four or two conical spinescent projections 

 formed by the persistent and hypertrophiate sepals. Its single cell 

 contains but one seed the coats of which enclose a large incurved 

 embryo, with superior radicle and very unequal cotyledons : one very 

 small, squamiform ; the other large, fleshy. 3 Trapa consists of 

 aquatic herbs, of which two or three species, 3 living in Europe and 

 the warm parts of Asia and Africa, are distinguished. The slender 

 floating stems bear two kinds of leaves. 4 ' The lower, submerged, are 

 opposite, pinnatisect, not unlike finely pectinate roots. The upper, 

 floating on the surface of the water, are united in rosettes and nearly 

 lozenge-shaped, dentate, penninerved, with an elongate petiole which 

 is most frequently dilated superiorly in a spongy enlargement destined 

 to sustain the summit of the plant at the surface of the water. 5 The 

 flowers 6 are axillary, solitary, with a short and thick peduncle, 

 accompanied by two lateral sterile bracteoles. 



V. HALORAGIS SERIES. 



TXaloragis 1 (fig. 457-461) has tetramerous flowers, 8 most fre- 

 quently polygamous, more rarely hermaphrodite. In the latter, the 

 receptacle has the form of a sac with four to eight angles or longi- 

 tudinal ribs. On its margin is inserted a superior perianth, composed 

 of four sepals, two of which are lateral, 9 and four alternate petals, 

 imbricate or more rarely contorted. The stamens are inserted within 



1 Later the ovule undergoes a twisting move- 8 White or greenish, without lustre, 



ment which renders its raphe lateral. It has a 1 Haloragis~FoB.ST.Char. Gen. 61, t. 31. — Pom. 



double envelope, and is not unlike in form and Diet. viii. 854. — Lhér. Stirp. t. 82. — DC. Prodr. 



direction that of the common Box. iii. 66. — Endl. Atakt. t. 15 ; Gen. n. 6138. — B. 



- The other seed is early aborted, but its re- H. Gen. 674, n. 2. — H. Bn. Payer Fam. Nat. 376; 



mains are seen for a long time. Adaiisonia, xii. 22. — Cercodia Muke. Comm. 



3 Koxb. PI. Corom. t. 234.— Braam, Ic. Chin. Gcett. iii. (1780) 1. t. 1— GiERTN. Fruct. i. 164, 

 t. 22.— Oliv. FI. Trop. Afr. ii. 491.— Gren. et t. 32.— Cereodea Lamk. III. t. 319.— Gonocarpus 

 Godr. FI. de Fr. i. 588.— W alp. Rep. ii. 100. Thunb. Fl. Jap. 5, t. 15— G.-ertn. f. Fruct. 



4 For the study of the germination, and also 250, t. 25. — GouatocarpusW. Sped. 690. — Gon- 

 that of ramification, etc., consult the very beau- jocaipus Kœn. Ann. Bot. i. 546, t. 12, fig. 5, 6. 

 tiful work of Mirbel (Ann. Mus. xvi. 447, t. 19) — Gonioearpus DC. Prodr. iii. 67. 



and also that of Barnéoud mentioned above. 8 More rarely of three or five parts. 



5 Precisely the same disposition is met with 9 Sometimes nearly peltate, or slightly de- 

 in certain Ji/ssiaic which have quite the leaves curring under the point of insertion on the 

 of Trapa . When young, the leaves appear to floral receptacle. 



have two small stipules. 



