THE COMMON MARE’S-TAIL— continued. 
Hippuris is a glabrous plant with a creeping rhizome and erect, unbranched, 
jointed, tapering shoots bearing whorls of from six to twelve narrow entire leaves 
and minute sessile flowers, one in the axil of each of the upper leaves. The 
rhizome is buried in the mud and the shoots rise above water, so that, as in 
Myriophyllum , the flowers can be wind-pollinated. The plant sometimes occurs in 
running water, when it is wholly submerged and flowerless. The leaves, when 
short, terminate in a stiff, hard tip ; but in deep or running water they elongate, 
sometimes nearly to a foot in length, becoming at the same time flaccid and 
translucent with no hard tip. Internally, the stems have the central vascular axis 
and numerous air-spaces characteristic of submerged aquatics in general ; and whilst 
the short thick leaves above water have a cuticle, stomata on both surfaces, palisade- 
tissue, and several vascular bundles, the thinner and paler submerged ones have 
neither stomata nor cuticle, much less mesophyll, with no distinct palisade-tissue, 
and with but one vascular bundle. The calyx is an obscurely two-lobed ridge round 
the upper part of the inferior ovary : the stamen has a red anther ; and the style is 
tapering, pointed, and stigmatiferous throughout its length. 
This Flowering Plant presents so much superficial resemblance to the Horse- 
tails [Equisetum) , which are allied to the Ferns, that it is not surprising that their 
names have been constantly interchanged. The name Equisetum , from the Latin 
equus, a horse, and seta , a hair, is used by Pliny ; but Dodoens gave to the same 
cryptogamic plants the name Hippuris , from the Greek hippos , a horse, 
ovpa, oura, a tail, which Linne took for the Flowering Plant. Gerard and other 
herbalists called this latter Cauda equina fcemina or Female Horse-tail , as being lower- 
growing than Equisetum limosum Linne, which may sometimes be seen growing 
side by side with it. Modern botanists, as Dr. Prior points out, have followed 
Hudson in shifting the hyphen, making Female Horse-tail into Female-horse Tail , i.e. 
Mare's-tail. When, however, Tennyson, in his “ Aylmer’s Field,” writes of “ The 
pretty marestail forest, fairy pines,” he is, no doubt, thinking of the crowded 
societies of Equisetum maximum or the drooping E. sylvaticum , which resemble 
a pine-forest far more than Hippuris can ever do. So too such popular names as 
Bottle-brush , Cat' s-tail, Joint-weed , and Paddock Pipes , i.e. Frog’s-pipes, are bestowed 
upon both plants. 
