Hippuris. ] XXXIV. HALORAGES. 175 
scarcely perceptible border to the calyx, and reduced to 1 stamen, 1 subu- 
late style, and 1 ovule and seed. 
1, H. vulgaris, Linn. (fig. 395). Common Marestail.—An aquatic 
plant with a perennial rootstock, and erect, annual, simple stems, the upper 
part projecting out of the water sometimes to the height of 8 or 10 inches, 
and crowded in their whole length by whorls of from 8 to 12 linear entire 
leaves ; the submerged ones, when in deep streams, often two or three 
inches long, gradually diminishing till the upper ones are less than half an 
inch. Flowers minute, sessile in the axils of the upper leaves, consisting of 
a small globular or oblong ovary, crowned by a minute, scarcely preceptible 
border, on which is inserted a very small stamen, and from the centre of 
which proceeds a short, thread-like style. Fruit a little, oblong, 1-seeded 
nut, scarcely a line in length. 
In shallow ponds, and watery ditches, over the greater part of Europe, 
Russian and central Asia, and North America, especially in high latitudes, 
reappearing in Chili and Tierra del Fuego. In Britain, not near so 
frequent as Myriophyllum and Ceratophyllum, except in Ireland, where it 
is said tobe common, 7. summer. The whole plant has a general re- 
semblance, although no affinity, to some of the more slender species of 
Equisetum, often called Horsetails or even Marestails. 
XXXV. UMBELLIFERZ. THE UMBELLATE FAMILY. 
Herbs, or in a few exotic species, shrubs, with alternate 
leaves, often much cut or divided ; the footstalk usually dilated 
at the base, but no real stipules. Flowers usually small, in 
terminal or lateral umbels, which are either compound, each 
ray of the general umbel bearing a partial umbel, or more rarely 
simple or reduced to a globular head. At the base of the 
umbel are often one or more bracts, constituting the involucre, 
those at the base of the partial umbel being termed the ¢nvolucel. 
Calyx combined with the ovary, either entirely so or appearing 
only in the form of 5 small teeth round its summit. Petals 5, 
inserted round a little fleshy disc which crowns the ovary, 
usually turned in at the point, and often appearing notched. 
Stamens 5, alternating with the petals. Ovary 2-celled, with 
one ovule in each cell. Styles 2, arising from the centre of the 
disk. Fruit when ripe, separating into 2 one-seeded, indehiscent 
carpels, usually leaving a filiform central axis, either entire or 
splitting into two. This axis, often called the carpophore, is 
however sometimes scarcely separable from the carpels. Each 
carpel (often called a mericarp, and having the appearance of 
a seed) is marked outside with 10, 5, or fewer, prominent 
herves or ribs, occasionally expanded into wings, and under- 
neath or within the pericarp are often longitudinal channels, 
called vittas, filled with an oily or resinous substance. Embryo 
