Udora. HYDROCHARIDACEiE. 265 



of 4 minute globules cohering together. Perfect flowers expanding on the surface, which 

 they reach by means of their filiform perianth-tube, which varies in length according to the 

 depth of the water, being sometimes a foot long. Spathe cleft about half way down ; the 

 segments acute. Lobes of the perianth roundish-obovate, spreading, the three inner ones 

 less petaloid than the others. Stamens mostly 3, but varying to 5, 6 or more : anthers 

 yellow, oblong, nearly sessile. Ovary oblong, attenuated upward ; the 3 placentae projecting, 

 each bearing 2-3 ovoid ascending orlhotropous ovules : stigmas usually three, spreading, 

 purple, more or less deeply 2-lobed. Ripe fruit not seen. 



Sluggish streams and shallow lakes : frequent. Fl. July and August. I have never been 

 so fortunate as to detect the sterile flowers of this plant, and have described them from speci- 

 mens communicated to me by Dr. Engelmann of St. Louis. I have found, near Princeton, 

 New Jersey, the Udora bearing flowers which presented a remarkable anomaly. The ovary 

 appears of the ordinary form ; but on laying it open, there are seen three and sometimes four 

 bodies resembling styles, which originate at the base of the placentae, and, after rising some 

 distance, make a double curvature, and then terminate in a long papillose extremity, having 

 every appearance of a stigma, the latter being lodged in the slender tubular portion of the 

 ovary, just above the swollen base. These bodies (particularly the stigma-like portion) are of 

 bright purple color. The placentae bear ovules as usual, and at the summit of the flower 

 there are the regular segments of the perianth, stamens, and 3 large purple 2-lobed stigmas 

 as in the ordinary state of the plant. 



3. VALISNERIA. Michel. ; Endl. gen. 1209. TAPE-grass. 



[In honor of Antonio Valisneri, an Italian botanist.] 



Dioecious. Sterile fl. Spathe on a short scape, 2 - 3-parted. Flowers numerous, nearly 

 sessile, crowded on a conical receptacle. Perianth 3-parted. Fertile fl. Scape very 

 long, flexuous or spiral. Spathe tubular, 2-cleft, one-flowered. Perigonium 3-parted. 

 Staminodia 3 (petals of most authors), linear, one of them often 2-cleft. Ovary linear, 

 one-celled, with 3 parietal placentae : stigmas 3, nearly sessile, ligulate, 2-lobed. Fruit 

 elongated, cylindrical, crowned with the limb of the perianth. Seeds oblong-cylindrical. — 

 Stemless water-plants, with long narrow linear leaves. 



1. Valisneria spiralis, Linn. Tape-grass. Eel-grass. 



Leaves linear, obtuse, minutely serrulate. — Linn. sp. 2. p. 1015; Hook. hot. misc. t. 30 

 (fertile), ^ t. 33 (barren), and fl. Bor.-Am. 2. p. 192. V. Americana, Michc. fl. 2. p. 220; 

 Pursh, fl. 2. p. 602 ; Nutt. gen. 2. p. 230 ; Ell. sk. 2. p. 666 ; Bigel. fl. Bost. p. 364. 

 V. spiralis, var. Americana, Torr. compend. p. 365 ; Beck, hot. p. 342 ; Darlingt. fl. Cest. 

 p. 557. 



[Flora — Vol. 2.] 34 



