i88i.] BOTANY FOR GARDENERS. 31 



channel through which the vessels of the leaf are connected with those of the 

 stem : it is formed of one or more bundle of spiral vessels and woody tissue, 

 enclosed in a cellular integument. It is often absent, and then a leaf is called 

 sessile, as the well-known spotted Orchis. The leaves of the Common Primrose 

 (Primula vulgaris) are also sessile. When the petiole becomes dilated and 

 hollowed out at its upper end, the lamina being articulated with, and clos- 

 ing up its orifice, as in Sarracenia and Nepenthes, it is called a pitcher or 

 Ascidium ; if it is unclosed, and is a mere sac, as in the Utricularia, it is 

 termed amjnilla. Sometimes the petiole has no lamina, or is lengthened beyond 

 the lamina and retains its usual cylindrical or taper figure, but becomes long, 

 and twists spirally; such a petiole is called a tendril. Excellent examples of 

 tendrils are furnished in the Vine, Pea, and Clematis. The form of the simple 

 leaf is extremely variable. The leaves of the tall Convolvulus are cordate ; of the 

 Ground Ivy (Glechoma), reniform ; of the Mezereeou and Plantain, lanceolate ; 

 of the Daisy, spathulate ; of the Iris, ensifarm ; of the Sheep's Sorrel, sagittate ; 

 of the Arum, hastate ; of the Whortleberry, retuse ; of the Tulip-tree, truncate ; 

 of the Horse-chestnut, digitate; of the Passion-flower, ^aZ7?i«^e ; of the Christ- 

 mas Rose, pedate ; of the Water Milfoil, pectinate. 



In reference to size, the leaf varies from a point to an expansion of immense 

 magnitude. The leaves of the Palmyra Palm (Borassus flabelliformis) will 

 each shelter twelve persons ; beneath a leaf of the Corypha umbraculifera, a 

 person on horseback can be completely sheltered ; and a leaf of the Pandanus 

 longifolia has often been grown 15 feet long in this country. Again, on the 

 contrary, leaves are almost as thin as a hair : native examples of this are fur- 

 nished by some of our aquatic Ranunculi. The leaves of Myriophyllums are also 

 extremely small. By the foregoing remarks it will thus be seen that in con- 

 sistency leaves vary from a gossamer tissue to the enormous ones of the Palms, 

 &c,, I have mentioned. A perfect plant consists almost entirely of leaf- forma- 

 tions, which are as follows: (a) The lower stem-leaf; (6) true stem-leaf; (c) 

 upper stem-leaf ; {d) calyx-leaf ; (e) flower-leaf ; (/) stamen-leaf, and {g) fruit- 

 leaf formations. An explanation of the above seven terms is necessary. The 

 first formation (a) is characterised in form by a broad base and limited height; 

 in substance by a frequently fleshy cartilaginous or leathery consistence, and a 

 dark colour. These characters show that this, the lower stem-leaf formation, 

 is wholly or partially excluded from the influence of light and air, and serves for 

 the fastening of the plant in most cases, {b) The second formation, or that of 

 the true stem-leaves, is generally a very extensive structure, characterised by 

 the multiplicity of its organs, which are properly called leaves, and are distin- 

 guished from the lower stem-leaves by a greater longitudinal extension, with 

 less breadth of base, expansion at the upper and contraction at the lower ends, 

 a more membranous nature, and a green colour. The third (c), or upper stem- 

 leaf formation, which consists principally of sheaths, bracts, glumes, &c., in 

 some degree similar to the first formation, but are distinguishable from that 

 formation by the much more delicate structure and narrower base ; they pre- 

 sent but little that is strikingly remarkable, in consequence of their very small 

 size. The fourth {d) formation is that of the calyx-leaf, or more popularly 

 known as sepals, and are much more massive, coarser, greener than the last 

 formation (c) ; they have a broader base, are equally destitute of any incision, 

 and rarely possess an expansion. The fifth (e), or the formation of the flower- 

 leaf or petals, is especially distinguished from all others by the delicacy of 

 its tissues, as well as by the purity and diversity of colours. Flower-leaves, or 

 petals, are generally longer than calyx-leaves, but narrower at the base ; in 



