FLOWER

a specialized shoot of limited growth bearing the e ential organs of reproduction, the stamens and carpels, apically. The portion of the shoot which bears the stamens and carpels is termed the receptacle, and as a rule also carries two other sets of leaves —the sepals, protective in character and collectively forming the calyz, and the petals, often brightly colored and insect-attracting, termed the corolla. Where, as in the Liliaces, the calyx and corolla do not differ in appearance, they are grouped together as the perianth, The calyx is primarily protective, and so is often tough and may be covered. with hairs. In some cases its functions cease with the opening of the flower, in the poppy, in which the petals are shed as the bud unfolds; in most othe! cases its functions extend throughou the life of the flower, whilst in a fe (e.g., Rosacee, Leguminosz) it is per sistent and protects the developing fruit. Certain of the Ranunculaces, such delphinium and aconitum, have dev i oped petaloid brightly colored calices, Owing to the reduction and modification of the petals as nectaries, whilst the catkin-bearing flowers are devoid of calyx, their place being taken by overlapping scales.; Stamens and Petals.—The sepals in the higher groups are coherent or gamosepalous, this usually being accompanied | by a similar fusion of the petals, termed | gamopetaly. Whilst most flowers are|N-Yradially symmetrical or actinomorphic, | there is in nearly all groups a tendency | to bilateral symmetry or zygomorphy, owing to the development of nectar if. erous spurs or other honey-protecting devices. Thus we have the larkspur and the monkshood in the Ranunculace, Papilionacez, such as the sweet pea, the Labiatee, Scrophulariaces, and many others, exhibiting this character, which tends to prevent all but those] insects efficient as pollen-bearers from | obtaining the secreted honey. The stamens are numerous in many groups (Rosaces, Ranunculace) and are ar-| ees ie ppally a, es there is SS general ndency to reduction in most groups| correlated with the greater specialization of the remaining floral members. | Pollination.—The carpels bear one or | more ovules, and at the apex po e a specialized receptive portion for the] pollen grains, which is termed the] stigma, and is often of either a sticky or | 2 brush-like character. Each ovule when | mature contains a central embryo-sac of in which there are three nuclear groups: (1) the egg-cell, forming the embryo on fertilization, and two synergide; (2) the} polar nuclei, which, on fusion with the second male nucleus, form helicoid and scorpioid cymes, which result from unilateral branching. ‘The raceme which _ develops se ile flowers is termed a spike (e.g. barley), whilst if the main ' axis is foreshortened so that all the florets appear to spring from one level, like the cee tu ac Pomme a i eater results m™m iferee). inally, by the development of se ile flowers on the a ane Spicy | Gastencd | @ capitulum is produced such as occurs | in the p dandelion, D daisy, and other | Composite,