HYDROCHARIDACEiE. (FROG’s-BIT FAMILY.) 463 
shed their pollen to fertilize the stigmas, which are raised to the 
surface by the excessively prolonged calyx-tube, which varies in 
length according to the depth of the water. (Name from t&op 
water.) 
1. U. Canadensis, 
finely serrulate (£' long).— 
^ utt * Leaves oblong-ovate or lanceolate, 
Ponds and slow streams. July. 
3. VALLISNEBIA, Micheli. Tape-grass. Eel-grass. 
Flowers strictly dioecious: the sterile numerous and crowded in 
a head on a conical receptacle, inclosed in an ovate at length 3- 
valved spathe which is borne on a very short scape: stamens 
mostly 3. Fertile flowers solitary and sessile in a tubular spathe 
which is borne on an exceedingly long scape. Perianth (calyx) 
3-parted in the sterile flowers; in the fertile with a linear tube 
coherent with the 1-celled ovary but not extended beyond it, 3- 
lobed; lobes obovate, and 3 linear small petals alternate with 
them. Stigmas 3, large, nearly sessile, 2-lobed. Ovules very 
numerous on 3 parietal placentae, orthotropous! Fruit elongated, 
cylindrical, berry-like. — Stemless plants, with long and linear 
grass-like leaves, growing entirely under water. The staminate 
clusters being confined to the bottom of the water by the shortness 
of the scape, the flower-buds themselves spontaneously break away 
from their short pedicels and float on the surface, where they ex¬ 
pand and shed their pollen around the fertile flowers, which are 
raised to the surface at this time : fertilization being thus accom¬ 
plished, the thread-form fertile scapes (2-4 feet long according to 
the depth of the water) coil spirally and draw the ovary under 
water to ripen. (Named in honor of Valhsneri, an early Italian 
botanist.) 
1- V. spiralis, L. Leaves linear, thin, long and ribbon-like 
(l°-2° long), obscurely serrulate, obtuse, somewhat nerved and net- 
ted-veined. — Common in slow rivers, &c. August. 
Order 115. ORCHLDACIL®. (Orchis Family.) 
Herbs , distinguished by their irregular flowers , 6-merous 
perianth adherent to the l-celled ovary with 3 parietal pla¬ 
centa, gynandrous stamens (only 1 or 2), and pollen coher¬ 
ing in waxy or mealy masses. Fruit a 1-celled 3-valved 
