The keel, or carina sterni, is formed as a direct cartilaginous outgrowth of the body of the sternum, ossifying from a special centre.
(I) first antenna; (6) tergum; (2) compound (7) biramous eye; feet; (3) liver; (8) carina; (4) simple eye; (9) cement (5) scutum; gland.
W, wax-yielding surface, covering true gland; s, septem, or carina; wh, webbed hairs.
In his book on the fertilization of flowers, Hermann Muller distinguishes four types of papilionaceous flowers according to the way in which the pollen is applied to the bee: (I) Those in which the stamens and stigma return within the carina and thus admit of repeated visits, such are the clovers, Melilotus and laburnum.
- Flower of Pea (Pisum sativum), showing a papilionaceous corolla, with one petal superior (st) called the standard (vexillum), two inferior (car) called the keel (carina), and two lateral (a) called wings (alae).
Carina may perform a similar office, and then the aestivation is carinal, as in the Judas-tree (Cercis Siliquastrum).
3, A part of the carina or keel.