Apical plates by a stretch of dorsal integument containing skeletal elements; the opening of the water-vascular system (madreporite) is not connected with a definite apical plate or system of plates.
Accepting the homology of these apical systems with the calycinal system, the theory would regard the aboral pole of a sea-urchin or starfish as corresponding in everything, except its relations to the sea-floor, with the aboral pole of a fixed echinoderm.
An apical senseorgan, a simple gut, protonephridia and schizocoele.
Dictyota sp., apical cells immediately after dichotomy.
In Dictyotaceae the apical cell occasionally divides longitudinally, and thus the dichotomous branching is provided for.
In Coleochaete the oogonial wall is drawn out into a considerable tube, which is provided with an apical pore, and this tube has a somewhat similar appearance to the imperforate trichogyne of Florideae to be hereafter described.
In the ripe seed the integument assumes the form of a fleshy envelope, succeeded internally by a hard woody shell, internal to which is a thin papery membrane - the apical portion of the nucellus - which is easily dissected out as a conical cap covering the apex of the endosperm.
In other cases, again, a group of two or four prismatIl cells takes the place of the apical cell.
Further growth in length of the stem is thenceforward confined to the apical growing point situated between the cotyledons.
It is closed except at the apex, and contains the female spikelet, the stalks of the male inflorescence and the long styles emerging through the small apical orifice.