xviii OUTLINES OF BOTANY. 



169. Tendrils (cirrhi) are usually abortive petioles, or abortive peduncles, or sometimes 

 abortive ends of branches. They are simple or more or less branched, flexible, and coil more or 

 less firmly round any objects .within their reach, in order to support the plant to which they 

 belong. Hooks are similar holdfasts, hut of a firmer consistence, not branched, and less coiled. 



170. Thorns and Prickles have been fancifully called the weapons of plants, k Thorn 

 or Spine is the strongly pointed extremity of a branch, or abortive petiole, or abortive peduncle. 

 A Prickle is a sharply pointed excrescence from the epidermis, and is usually produced on a 

 branch, on the petiole or veins of a leaf, or on a peduncle, or even on the calyx or corolla. 

 When the teeth of a leaf or the stipules are pungent, they are also called prickles not thm-ns. A 

 plant is spinous if it has thorns, aculeate if has prickles. 



171. Kairs, in the general sense, or the indumentum (or clothing) of a plant, include all 

 those productions of the epidermis which have, by a more or less appropriate comparison, been 

 termed bristles, hairs, down, cotton or wool, 



172. Hairs are often branched. They are said to be attached by the centre, if parted from the 

 base, and the forks spread along the surface in opposite directions ; pluviose, if the branches are 

 arranged along a common axis, as in a feather ; stellate, if several branches radiate horizontally. 

 These stellate hairs have sometimes their rays connected together at the base, forining little flat 

 circular disks attached by the centre, and are then called scales, and the surface is said to be 



scaly 01 1 -^- 



173. The Epidermis, or outer skin, of an organ, as to its surface and indumentum, is 

 smooth, when without any protuberance whatever. 



glabrous, when without hairs of any kind. 



striate, when marked with parallel longitudinal lines, either slightly raised or merely 

 discoloured. 



furrowed (sulcate) or ribbed (costate) when the parallel lines are more distinctly raised. 



rugose, when wrinkled or marked with irregular raised or depressed lines. 



umbilicate, when marked with a small round depression. 



umbonate, when bearing a small boss like that of a shield. 



viscous, viscid, or glutinous, when covered with a sticky or clammy exudation. 



scabrous, when rough to the touch. 



tuberculate or warted, when covered with small, obtuse, wart-like protuberances. 



muricate, when the protuberances are more raised and pointed but yet short and hard. 



echinate, when the protuberances are longer and sharper, almost prickly. 



setose or bristly, when bearing very stiff erect straight hairs. 



glandular-setose, when the setse or bristles terminate in a minute resinous head or drop. In 

 some works, especially in the case of roses and robus, the meaning of setce has been restricted to 

 such as are glandular. 



glochidiate, when the setse are hooked at the top. 



pilose, when the surface is thinly sprinkled with rather long simple hairs. 



hispid, when more thickly covered with rather stifif hairs. 



hirsute, when the hairs are dense and not so stiff. 



downy oi pubescent, when the hairs are short and soft ; perbulent, when slightly pubescent. 



strigose, when the hairs are rather short and stiff, and lie close along the surface all in the 

 same direction ; strigillose, when slightly strigose. 



tomentose or cottony, when the hairs are very short and soft, rather dense and more or less 

 intricate, and usually white or whitish. 



woolly {lanate), when the hairs are long and loosely intricate, like wool. The wool or 

 tomentum is said to he Jloccose when closely intricate and readily detached, like fleece. 



mealy i/arinose), when the hairs are excessively short, intricate and white, and come off 

 readily, having the appearance of meal or dust. 



canescent or hoary, when the hairs are so short as not readily to be distinguished by the 

 naked eye, and yet give a general whitish hue to the epidermis. 



glaucous, when of a pale bluish-green, often covered with a fine bloom. 



174. The meanings here attached to the above terms are such as appear to have been most 

 generally adopted, but there is much vagueness in the use practically made of many of them by 

 different botanists. This is especially the case with the terms pilose, hispid, hirsute, pubescent, 

 and tomentose. 



175. The name of Glands is given to several different productions, and principally to the 

 four following : — 



1. Small wart-like or shield-like bodies, either sessile or sometimes stalked, of a fungous or 

 somewhat fleshy consistence, occasionally secreting a small quantity, of oily or resinous matter, 

 but more frequently dry. They are generally few in number, often definite in ,their position and 

 form, and occur chiefly on the petiole or principal veins of leaves, on the branches of inflores- 

 cences, or on the stalks or principal veins of bracts, sepals, or petals. 



2. Minute raised dots, usually black, red, or dark-coloured, of a resinous or oily nature, 

 always superficial, and apparently exudations from the epidermis. They are often numerous 

 on leaves, bracts, sepals, and green branches, and occur even on petals and stamens, more 

 rarely on pistils. When raised upon slender stalks they are called pedicellate (or stipitate) 

 glands, or glandular hairs, according to the thickness pf the stalk, 



