CXII. GRAMINEJE 661 



sheaths have fallen, pierce through the sheath at its base. These rootlets 

 rarely reach the ground, and often become hard and spinescent. 



The leaves are distichous, and consist of a tubular sheath, split to the base, 

 and a linear-oblong or lanceolate blade with a midrib and numerous longi- 

 tudinal veins (tibro- vascular bundles i, usually of two classes, stout or coarse 

 and thin, generally 5-9 thin between two stout nerves. The blade is joined 

 to the sheath by a short petiole. Half-way between two longitudinal nerves 

 and parallel to them is a transparent band, due to several lines of large cells, 

 belonging to the upper epidermis, which are frequently, but not in all cases, 

 tilled with bright colourless masses of Silica (Silicon dioxide i. All Bamboo 

 leaves have transverse veins, consisting of wood-tibms, which run across from 

 one longitudinal nerve to the next, straight, oblique, or with a bend in the 

 middle. In many species these transverse veins are conspicuous, particularly 

 on dry leaves, but they can usually be distinguished, under the lens or micro- 

 scope, as bright translucent dots at the point where they cross the baud of 

 Silica cells. (Translucent glands, Gamble.) Pieces of dry 1. boiled in water, 

 and examined in glycerine, often show the transverse veins : they can be made 

 more conspicuous by bleaching reagents or by scraping off part of the tissue 

 tilled with chlorophyll. Ou the underside of the leaf the epidermis has numer- 

 ous solid protuberances or haii-s, which usually are short and thick-walled, in 

 some species long and soft. The leaves beiug distichous, an inner and an outer 

 edge may be distinguished ; on the inner edge (in many species on both edges'* 

 we find as a rule a colourless band, fringed with longer or shorter thick- walled 

 sharply-pointed hairs, while the outer edge is often rough ou the upper side, 

 with lines of short rigid hairs along the outermost veins. 



The identification of many species, when leaves only are available, ma;' be 

 facilitated by counting the number of longitudinal nerves on | in. In most 

 genera the nunilicr varies between "20 and 50. D< inlrnr<ilnuitixaiv\ Melocalamus 

 have '20-80, and the following species have less than '24: Arundinaria 

 Walkeriana (leaf 1— 1§ in. wide). .1. Ebokeriana . ,',-li in.), Bambusa khasi- 

 (ina (1—1 .V in.), B. Griffithiana (3 in.), Pseudostachyum polymorphum 

 (1-2 in.), Dinochloa McClellandi 2—4 in.), D. andamanica (1-2 in.), Teino- 

 stachyum Helferi (li— 3i in.). T. Wightii (1-3 in.), Cephalostachyum 

 capital a in (1—2 in. i , C. latifolium '2—1 in. . C. Fuchsianum 2-4 in. . Meo- 

 canna bambusoides I- 1 in . As ma)' be expected, many broad-leaved 

 species have the longitudinal n. far apart, but there also are broad-leaved 

 species with the longitudinal nerves close together. For most species the 

 number of n. on \ in. has here been stated. Conspicuous transverse veins are 

 found in Phyllostachys, in the majority of Arundinaria, in Pseudostachyum 

 polymorphum, and a few other species. When close together they form 

 squares or short rectangles with the longitudinal nerves < Plu/llostachys, 

 Arundinaria densifolia, racsmosa, elegans, jaunsarensis, hirsute . 

 In counting the number of nerves on J in., only full-grown 1. should be 

 selected, and the nerves must be counted in the middle, half-way between 

 base ami tip. If this is done the results will be found to be fairly uniform. 

 whether the leaf selected is broad or narrow. Loaves grown under excep- 

 tional conditions, for instance, in a hothouse, are apt to bo irregular, and should 

 be avoided. The nerves are of ten closer together near the edge of the Leal, 

 hence an average should be struck between the countings near the edge and 

 the midrib. Care must be taken to count the nerves only, not the translucent 



lines of silica cells, a strong lens or a small microscope should lie used ; and 

 in the case of dr\ leaves it is advisable to boil a small piece in water and 

 place it in glycerine. 



PI. mostly bisexual, in distich. .us spikelets, usually arranged in huge 

 panicles. The spikelet consists of a number of distichous brads or glumes, 

 the lower and sometimes the upper being empty. Each flowering glume 

 bears in its axil the palea. a membranous, usually transparent bract, which 

 has its back appressed to the axis of the spikelet and which, except when 



