550 PART III. — THE CLASSIFICATION OF PLANTS. 



glume is usually rudiineutary. In all the other genera the side of the spikelet 

 is directed towards the main axis, and there are two glumes. In Agopyrum, the 

 palese adhere and fall off with the fruit : A. repons, the Couch-Grass, is common 

 everywhere, and is a troublesome weed on account of its spreading rhizome. 

 Secale cereals, the Rye, has 2flowered spikelets and narrow awl-shaped glumes. 

 In Nardus stricta, the Mat-Grass, the two rows of spikelets converge laterally ; 

 the glumes are rudimentary ; there is but one stigma ; the leaves and haulms 

 are rough ; it grows on moors. Triticum, the Wheat, has 3- or more flowered 

 spikelets, with ovate glumes. Three species are cultivated, T. vionncoccuiu, 

 T. sativum, and T.pnlonicum ; in the first species the terminal spikelet is abortive. 

 The following varieties of T. s/ifiuMW are cultivated ; T. vulgare, the common 

 Wheat, with long glumes, which haveno keel, and T. turgidum, English Wheat, 

 with short keeled glumes ; 2'. con>pactuvi, the Dwarf Wheat, with short, stout 

 spikelets ; and T. din^um, the Hard Wheat, known by its long rigid awns ; all 

 these varieties have a wiry floral axis (hence sometimes described as T. sativum 

 ttnix), and the fruit easily falls out of the glumes, and in all but T. durum there 

 are awned and un-awned (beardless) forms: T. Spilfa, the Spelt, which has an 

 almost quaflrangular spike, and T. dicoccum, with a compact spike, have a brittle 

 floral axis, and the fruit is firmly enclosed by the glumes. In all the species 

 the length of the awn varies very much. Hordeum, the Barley, has 3 single- 

 flowered spikelets inserted together in one depression on the floral axis. H. 

 murinnm is common on the roadside and on walls. The following varieties of 

 H. sativum are cultivated : H. vulgare and H. hexastichum, with only fertile 

 spikelets ; in the latter species the spikelets are all equally distant, and are 

 therefore arranged in six rows ; in the former sj^ecies the median spikelets are 

 nearer together, and the lateral ones more distant, so that they are described as 

 being in four rows : further, H. distichum is the two-rowed Barley, the lateral 

 spikelets of which are $ , so that the fruits are arranged in two rows. The 

 fruit usually adheres to the palea; the embryo has no epiblast. The genus 

 Elymus, the Ljme-Grass {E. arevaritis, Brilit-h) belongs to this tribe, as also 

 Pariana, a tropical genus remarkable for its numerous stamens. 



Tribe 11. Bamhusece : spikelets 2- or many-flowered, rarely 1-flowered, in 

 racemes or panicles, clustered at the nodes of the branches of the inflorescence : 

 glumes 2 or many, becoming larger upwards, but shorter than the nearest palea 

 (see Fig. 353^): stamens generally 6. Large Grasses, known as Pamboos, 

 having perennial aerial shoots with often shortly peiiolate leaves, growing mostly 

 in the Tropics. The most familiar genera are Arundinaria and Bambusa. 



Order 2. CvPERACEiE. The leaves are arranged in three rows 

 on the stem : perianth 0, or of 3-6 or more bristles or scales : the 

 androeeium consists typically of two trimerous whorls, though one 

 whorl (the inner) is absent in some genera : the gynseceum is 

 typically trimerous, though it is sometimes dimerous : ovary 

 unilocular : ovule erect, anatropous ; the embryo is enclosed in 

 the endosperm. 



Tribe I. Scirpoidea : flowers ^ ; perianth 0, or of bristles : glumes disti- 

 chous : the odd carpel is anterior. The spikelets are often arranged so as to 



