Seeds originate from anatropous, unitegmic
and tenuinucellate ovules (Figure 1A).
The ovule is of anatropous type and unitegmic
Gymnosperm ovules are always unitegmic
and also orthotropous so that the podocarp ovule may be seen as anticipating the anatropous ovule of flowering plants, the second integument being responsible for the necessary asymmetric growth.
Ovule: (0) orthotropous, bitegmic; (1) anatropous or hemianatropous, bitegmic; (2) anatropous, unitegmic
(Davis, 1966; Palkovic, 1974; Orchard, 1975; Corner, 1976; Cronquist, 1981; Dahlgren & Thorne, 1984; Webb & Gornall, 1989; Kubitzki, 1993b).
The ovules of cycads are unitegmic
(Chamberlain, 1935; Singh &
Ovary (2-)4-5(-14) carpellate, superior to inferior, with usually axile to intruded parietal placentation, rarely apical or basal; ovules 1 to many per carpel, anatropous to nearly campylotropous, unitegmic
, tenuinucellate, the embryo sac usually of the Polygonum type; style short to long, hollow, sometimes expanded apically; stigma truncate to capitate or slightly to strongly lobed, sometimes cup shaped, funnel shaped, or flabellate to pinnatifid.
Furthermore, most tenuinucellate dicotyledons are also unitegmic
, as Dablgren (1975) noted, whereas the majority of "primitive" dicotyledons and monocotyledons have bitegmic ovules (Endress, 1990, 1994; Dahlgren & Clifford, 1982).
Ovules 1 to many in each locule, anatropous to hemitropous, or amphitropous; unitegmic
, simple, tenuinucellar or pseudocrassinucellar (in Asclepiadaceae), usually without an integumentary tapeturn; endosperm development usually nuclear, rarely cellular.