CLXXXVI.— THE MARSH PENNYWORT. 
Hydrocotyle vulgaris Linne. 
T HE Family Umbellifer<e is not only by far the largest Family in the Order 
Umbelliflora , but is one of the more considerable and most sharply defined 
groups of Flowering Plants. It comprises some 1,400 species in about 180 genera 
and is cosmopolitan in its distribution, although best represented in the North 
Temperate Zone. Thirty-five genera and fifty-eight species of the Family belong to 
the British flora, of which twelve, all belonging to distinct genera, are represented on 
this and the twelve following Plates. 
Although generically and specifically difficult to discriminate, the plants of this 
Family present for the most part such marked general characters as to be easily 
recognised as such. They are mostly herbaceous, though often of considerable size : 
they have stout, often fluted, stems, of which at least the internodes become hollow 
by the rupture of the pith in their rapid growth ; and their leaves are generally 
scattered, exstipulate, sheathing at the base, and bi-, or tri-, pinnate. Their flowers 
are usually small, polysymmetric, pentamerous, white or yellow, perfect and grouped 
in compound umbels ; and they have usually an involucre of bracts at the base of 
the primary umbel and involucels or smaller secondary involucres below each of its 
umbellules or secondary — or, as they are often termed, partial — umbels. In some 
few genera, however, of which hydrocotyle and Eryngium occur in Britain, the 
inflorescence is a simple umbel. 
The superior calyx consists of five much-reduced sepals, of which the odd one 
is posterior : the five petals have usually inflexed points ; and there is one whorl of 
five stamens. The petals and stamens are epigynous, the receptacular tube being 
adherent to the inferior ovary, and honey is freely secreted from a fleshy epigynous 
disk. The flowers are markedly protandrous and are mainly cross-pollinated by flies. 
The fruit is dry and consists of two united, one-seeded carpels placed antero- 
posteriorly, one at the back of the flower, that is, and one at the front, crowned by the 
fleshy epigynous disk and two distinct styles. In this type of fruit, technically known 
as a cremocarp or inferior schizocarp , the two carpels generally adhere by their flattened 
inner faces (which form what is termed the commissure) to a central axis or carpophore , 
which is often Y-, or V-, shaped ; and, when ripe, they break away from this, from 
below upward, separating into two one-seeded mericarps. These are each marked 
by vertical ridges, of which five, known as primary ridges , are more universally 
present and usually the more prominent, though there may also be four secondary 
ridges between them. In the pericarp or wall of the fruit there are often long narrow 
sacs called vitta containing coloured essential oil, generally situated in the furrows 
between the primary ridges, two of them, however, being commonly on the commis- 
sural surface or surface of contact of the two mericarps. There is only pendulous 
seed in each carpel, containing horny albumen, and it is important to notice whether 
