_x Palea distinctly bifid at the apex: awn nearly twice its length. A very small grass about six inches high: leaves subulate, fine and short._ _A. caryophyllea_, L. _xx Paleæ almost imperceptibly bidentate: awn not much longer than palea. About 12-18 inches high: leaves inrolled._ _A. flexuosa_, L. Other species of _Aira_, with more condensed inflorescences, are dealt with on p. 112. _Agrostis_ is distinguished by the leaves and one-flowered spikelets (see p. 104). _Poa_ and _Catabrosa_ have no awns. CHAPTER VIII. THE FRUIT AND SEED. The stigma of an ordinary grass consists of two divaricating plume-like structures composed of thin-walled cells. When the paleæ open these stigmatic plumes protrude, one on either side, and readily catch pollen shed from the dangling stamens and carried by the wind, and since the pollen of the same flower is usually shed at a time when the stigmas of many neighbouring plants are mature, there is every opportunity for cross-fertilisation. (Fig. 33.) In some cases, however, e.g. _Anthoxanthum_, _Alopecurus_, the flowers are proterogynous, the stigmatic plumes being ready for pollination some time before the pollen is shed from the anthers of the same flower; whereas in most of our grasses the pollen begins to scatter before the stigmas are ready (protandrous). Among exotic grasses, many are diœcious or monœcious--i.e. the flowers contain stamens only or ovary only, on each plant, or on different inflorescences of the same plant respectively--and even in our own _Holcus_ and _Arrhenatherum_ this state of affairs is partially represented, since one flower of the spikelet is male only. In some grasses, e.g. Rye, however, it appears improbable that cross-fertilisation ever occurs, since the paleæ do not open, and the pollen falls on to the stigma direct; and in _Leersia_ and the foreign _Amphicarpum_ the spikelets are completely cleistogamous, those of the latter being on stalks close to the ground which push the flowers into the soil, where pollination and fructification are accomplished. Hybrid grasses are by no means uncommon. To say nothing of the numerous cross-bred Wheats and Barleys, artificial hybrids have been raised between Wheat and Rye. In the Maize an astonishing number of selected cross-breeds have been obtained, and, among others, certain forms in which the seeds have a violet outer layer and a sugary endosperm, are found to transmit these characters to the resulting seed of a variety which would normally have produced seed with white outer layers and starchy endosperm, if the pollen of the former is used on the stigma of the latter. Such direct influences of the pollen are termed _Xenia_.