NOTES ON THE FAMILY UMBELLIFERAE 95
The flowers have five petals, either with an apical notch
or inflected point; there are five stamens and two styles.
The calyx has five leaves, but these are sometimes wanting.
The petals are inserted on a little fleshy disc which secretes
honey; in some species there are five calycine teeth growing
from the disc, which are persistent in the ripe fruit (e.g.,
Oenanthe crocata).
The umbels are mostly compound, but sometimes lateral
(Apium nodiflorum), with bracts to the general and partial
umbels, referred to as involucres and involucels; in Aethusa
cynapium they are very pronounced, but in Pimpinella
saxifraga they are entirely absent.
The whole fruit is called a cremocarp, separating when
ripe into two similar parts called mericarps. The fruits are
of varying shapes and in some species they are covered with
small spines or bristles (e.g., Caucalis). They usually have
two styles growing from the top, and Eryngium is crowned
with a prickly calyx. In most fruits there are a number of
raised ribs and furrows, while others have a prominent outer
wing.
In Fig. a is illustrated a transverse section of the fruit of
Heracleum Sphondylium. Within the pericarp (covering of
the fruit) are longitudinal channels, called vittae; these
contain essential oil which is aromatic. The seed is inside
the carpel, closely adhering to the pericarp.