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Arundo. Phleum. Alopecurus. Holcus. Nardus. Agropyrum repens. | Lolium perenne. Brachypodium pinnatum. Dactylis. Cynosurus. Sesleria. |
Fig. 33. Arrhenatherum. 1 unopened and 2 open anther (× 12). 3, spikelets open and exposing the stamens and stigmas; 4, the pollen escaping and being dusted on to the stigmas (× about 5). Kerner.
As regards the flower proper, all our British grasses except Anthoxanthum (which has two only) have three stamens; but many exotic grasses have six stamens, and a few have a large number—even 40. The stamens have slender filaments and large versatile anthers, which dangle from between the paleæ when the flowers are mature, scattering their clouds of fine pollen in the wind (Fig. [33]).
All our ordinary grasses except Nardus—where there
Much interesting speculation has been expended in attempting to explain the morphological or theoretical significance of the parts of the spikelet of a grass. If we project the various organs on a flat surface in the form of a plan, keeping their relative positions intact, we obtain a diagram such as that shown in Fig. [34].
The comparison of numerous cases, and the study of the development of the parts on the microscopic growing point dissected out from young buds, have suggested that the inner and outer glumes are bracts, or covering leaves, at the base of the true spikelet. In like manner the two paleæ are bracteoles which subtend the flower proper. On this assumption they can be compared with the corresponding structures in other plants; whereas any attempt to compare the paleæ or glumes with the sepals and petals of ordinary flowers breaks down.
A curious interest attaches to the awns so often found on the backs of paleæ, and especially to those where the (sub-terminal) awn springs from just below the bifid apex (e.g. Avena, &c.).