Where the plant persists by means of a sympodial rhizome, or in Cyclamen by means of a tuber formed from the swollen hypocotyl.
In a colony formed by sympodial budding, a polyp always produces first a bud, which contributes to the system to which it belongs, i.e.
In the sympodial method of budding, on the other hand, the founder-polyp is of limited growth, and forms a bud from its side, which is also of limited growth, and forms a bud in its turn, and so on (figs.
Solitary polyps are unknown in this sub-order; the colony may be creeping or arborescent in form; if the latter, the budding of the polyps, as already stated, is of the sympodial type, and either biserial, forming stems capable of further branching, or uniserial, forming pinnules not capable of further branching.
SUB-ORDER HYDROIDEA CALYPTOBLASTEA (LEPTOsome with polyps always differentiated into nutritive and reproductive individuals(blastostyles) enclosed in hydrothecae and gonothecae respectively; with sympodial type of budding.