Sept. 1900.] 277 Miscellaneous. 



Lessons in Elementary Botany. IV. 



By J. 0. Willis. 



For those who wish to use a Flora, or list of the plants growing in a given 

 country, with descriptions— the first step towards finding out all about them— it is 

 necessary to give a few, at any rate, of the technical terms used in describing 

 leaves, as upon these a good deal depends the discrimination of plants. Those who 

 are not desirous of using a Flora — let us say Trimen's Flora of Ceylon— may 

 omit these. 



The few technical terms given here are sufficiently illustrated by the figures 

 in the Plate issued last month, to which reference should be made. 



Leaves are inserted upon the stem in various ways : they may be all at the 

 base {radical) or opposite, alternate, or in whorls. A complete leaf is made up of 

 leaf base (the swollen part adjoining the stem), stalk or petiole, and blade (or lamina, 

 as it is called in some older books). To the base are often attached a pair of out- 

 growths or stipules, one on either side, sometimes green and leaf-like, sometimes 

 represented by thorns, tendrils, scaly outgrowths, and so on. 



The leaf may be petiolate (stalked) or sessile (not stalked), stimulate (with) 

 exstipulate (without, stipules). The base or stalk may be sheathing. If the base 

 of the leaf is continued in a leafy outgrowth down the side of the stem the leaf 

 is decurrent. 



Leaves may be simple (with one blade, as in tea or cacao) or compound 

 (with more than one, as in many brambles, &c), and if the latter, either pinnate 

 (with leaflets arranged featherwise) or palmate (leaflets like the fingers of a hand). 



Leaves in shape (taking the general outline, regardless of notches) may be 

 needle-shaped, linear, . anceolate (about three or four times as long as broad, taper 

 ing mainly to tip), ovate (about 1J to 2 times as long as broad, tapering to tip {cordate 

 (heart shaped), kidney-shaped, and so on. If the tapering is more towards the base, 

 i.e., if the stalk in the figures were at the right instead of the left, the leaves would 

 be ob-ovate, ob-cordate, &c. 



The tip of the leaf may be acute (sharp pointed), obtuse (blunt ended), acu- 

 minate (tapering in curves to a point ; water runs easily off leaves of this kind, and 

 a pronounced acuminate point is sometimes called a drip-tip). An apex like a 

 (bottom right hand corner of plate) is called mucronate, like b apicidate, like c retuse. 



As regards notching : an absolutely un-notched leaf is entire ; if the edge 

 of the leaf be divided not more than half way down, the leaf is termed -fid, if h to 

 -partite, if more than f, -sect. The prefixes palmati- or pinnati- are put before 

 these terms to indicate which sort of notching occurs. If the leaves are simply 

 notched to less than \ of the depth, other terms are used, indicated by the figures, 

 viz., serrate, dentate, crenate, undulate. 



The surface of the leaf may be glabrous (without any hairs), downy or 

 pubescent (fine, soft hairs), hairy (coarser hairs), hispid (rough bristly hairs) 

 tmnentose (with a cottony felt of hairs), prickly, &c. 



The texture of the leaf may be thin, coriaceous (leathery) membranous, 

 succulent, Arc. 



Lsaves may be evergreen or deciduous (falling), &c. 



When a character comes between two of the terms used here, both are 

 employed, e.g., lanceolate-ovate. When it is nearly like one, sub- is placed in front 

 it, e.g., subacute. 



