apex, which is often produced into an upturned spine; microsporangia
microsporangia. Megasporophylls 40-200 in a crown and with (2)4(6)
microsporangia many, in groups of 2-5 and dehiscing by longitudinal
Each theca is built up of two pollen sacs (microsporangia
), dehiscing in various ways.
Evaporation is required for dehiscence of anthers and microsporangia prior to pollen release, and onset of cool, cloudy, and especially humid conditions leads to temporary suppression of pollen release (Sarvas, 1952, 1962; Sharp & Chisman, 1961; Silen, 1962; Ebell & Schmidt, 1964).
Consideration of the physical force required to entrain pollen grains from anthers, microsporangia, or foliage also supports the role of wind gusts and turbulent conditions in pollen dispersal.
The tribe, Torreyeae Janchen, consisting of Amentotaxus and Torreya, has arils adnate to the seed, abaxially positioned microsporangia, and leaves that contain resin.
The microsporangia are dorsiventral, but occasionally radial symmetry is displayed, at least near the strobilus apex, a condition also observed in the Cephalotaxaceae (Wilde, 1975).
The microsporocarps, which are about 2 mm in diameter, each produce 8-130 microsporangia, each containing 32 or 64 spores aggregated into 3-10 massulae (Moore, 1969; Shi & Hall, 1988).
The microsporangia break open, releasing spongy masses of microspores, or massulae, into the water.