174 THE MARESTAIL FAMILY. [ffippurfa 



II. HIPPURIS. MARESTAIL. 



A single aquatic species, distinguished as a genus from Myriophyllum 

 by its entire leaves, and by its flowers always without petals, with a 

 scarcely perceptible border to the calyx, and reduced to.l stamen, 1 subu- 

 late style, and 1 ovule and seed. 



1. H. vulgaris, Linn. (fig. 397). 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 2 or 

 3 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 perceptible 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. In Britain, not near so frequent 

 as Myriophyllum, except in Ireland, where it is said to be common. Fl. 

 summer. The whole plant has a general resemblance, although no 

 affinity, to some species of Equisetum, called Horsetails or even Mares- 

 tails, 



XXXV. UMBELLIFER-ffi. 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 involucel. 

 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 

 1 ovule in each cell. Styles 2, arising from the centre of the 

 disk. Fruit when ripe, separating into 2 1-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 



