The flowers are unisexual and monoecious, the numerous males borne in thick catkins proceeding from the side of last year's shoot.
The stamens become numerous (ten to forty) in the male flowers of a few monoecious genera (Pariana, Luzieta).
Monoecious, and bearing their male flowers in catkins, they are readily distinguished from the rest of the catkin-bearing trees by their peculiar fruit, an acorn or nut, enclosed at the base in a woody cup, formed by the consolidation of numerous involucral bracts developed beneath the fertile flower, simultaneously with a cup-like expansion of the thalamus, to which the bracteal scales are more or less adherent.
Cross-fertilization must of necessity occur when the flowers are structurally unisexual, as in the hazel, in which the male and female flowers are monoecious, or separate on the same plant, and in the willow, in which they are dioecious, or on different plants.
But it is clear that it becomes on this view increasingly difficult to explain the occasional occurrence of tetraspores on male, female and monoecious plants or the role of the carpospores in the life-cycle of Florideae.
The plant is monoecious, producing the staminate (male) flowers in a large feathery panicle at the summit, and the (female) dense spikes of flowers, or " cobs," in the axils of the leaves below, the long pink styles hanging out like a silken tassel.
The flowers are monoecious, and appear in Great Britain in February and March, before the leaves.
A few species, as we have seen, are monoecious or dioecious, while many are polygamous (having unisexual as well as bisexual flowers as in many members of the tribes Andropogoneae, fig.
Monoecious or dioecious.
Flowers monoecious or dioecious, unisexual, without a perianth, often in the form of cones, but never terminal on the main stem.
The flowers are dioecious, rarely monoecious, provided with one or two perianths.
In the case of unisexual flowers, whether monoecious, that is, with staminate and pistillate flowers on one and the same plant, such as many of our native trees - oak, beech, birch, alder, &c., or dioecious with staminate and pistillate flowers on different plants, as in willows and poplars, cross pollination only is possible.
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