xxii OUTLINES OF 



A strophiole or caruncle is a similar appendage proceeding frona the testa by the side 



of or near the funicle. 



165. The kllum is the scar left on the seed where it separates from the fiimcle. 

 The micropyle is a mark indicating the position of the foramen of the ovule (133). 



IRB. The Embryo (162) consists of the Radicle or base of the future root, one or 

 two Cotyledons or future seed-leaves, and the Plumule or future bud within the base 

 of the cotyledons. In some seeds, especially where there is no albumen, these se- 

 veral parts are very conspicuous, in others they are very difficult to distinguish 

 nntil the seed begins to germinate. Their observation, however, is of the greatest 

 importance, for it is chietly upon the distinction between the embryo with one or 

 with two cotyledons that are founded the two great classes of phsenogamous i)lants. 

 Monocotyledons and Dicotyledons. Cotyledons are said to be condwplicate when folded 

 once lengthwise ; contortupHcate when variously folded or twisted ; conferrumivAite 

 when so united that no line of separation can be traced. 



167. Although the embryo lies loose (unattached) within the seed, it is generally 

 in some determinate position with respect to the seed or to the whole fruit. This 

 position is described by stating the direction of the radicle next to or more or less 

 remote from the hilum, or it is said to be superior if pointing towards the sumnut 

 of the fruity ivfirior if pointing towards the base of the fruit, 



« 



§ 15. Accessory Organs. 



168. Under this name are included, in many elementaTy works, various external 

 parts of plants which do not appear to act any essential part either in the vegetation 

 or reproduction of the plant. They may be classed under four heads : Tendrils and 

 Hooks, Thorns and Prickles, Hairs and Glands, 



160. Tendrils (cirrki) 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, but of a 

 firmer consistence, not branched, and less coiled. 



170. THoms and Prickles have been fancifully called the weapons of plants, 

 A Thorn or Spine is the strongly i>ointed extremity of a l^auch, or abortive petiole, 

 or abortive peduncle. A Prickle is a sharply pointed excrescence from the epi- 

 dermis, and ia 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 thorns, A plant is spinous if it has 

 thorns, aculeate if it has prickles, 



171. Hairs, in the general sense, or the indumentum (or clothing) of a plant in- 

 clude all those productions of the epidermis which have, by a more or less appro- 

 priate comparison, been termed bristles, hairs, down, cottony or wool, 



172. Hairs are often branched. They are said to be attached hy the centre^ if 

 parted from the base, and the forks spread along the surface in opposite directions; 

 plumose, 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, forming little flat circular disks attached by 

 the centre, and are then called scales, and the surface is said to be scaly or lepidote, 



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

 smooth^ when without any protuberance whatever, 



glabrous^ when without hairs of any kind. 

 glahrcscent, glabrate, becoming glabrous. 



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

 merely discoloured. 



fwrrowed (sidcate) or rihhed (costate) when the parallel lines are more distinctly 

 raised. 



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



wnbilicate, when marked with a small round depression. 



UTnhonate, when bearing a small boss like that oi a shield. " 



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



icahrous, when rough to the touch. ■- - ^ •- - - * -•* » - . . ...^ i>* 



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