Xxii INTRODUCTION. 



hranous (skin-like), dry, or rarely succulent. It is sometimes expanded into taints, 

 or bears a tuft of hair^ cottouj or woolj called a coma. The inner coat is called the 



16i. The funicle is the stalk by which the seed is attached to the placenta. It is 

 occasionally enlarged into a membranous, pulpy, or fleshy appendage, sometimes spread- 

 ing over a considerable part of the seed, or nearly enclosing it, called an ariL A sfro- 

 jyJiiole or canmcle is a similar appendage proceeding from the testa by the side of or 

 near Uie funicle. 



165. The hihim is the scar left on the seed where it separates from the funicle. The 

 micropijle is a mark indicating the position of the foramen of the ovide (133). 



16G. The Embryo (162) consists of the Madlcle or base of the future root, one or 

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

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

 parts are very conspicuous, in others they are very difficult to distinguish until the 

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

 for it is cliiefly upon the distinction between the embryo with one or with two coty- 

 ledons that are founded the two great classes of phcenogamous plants. Mono cott/ led ons 

 and Dicotyledons, * 



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 kilum^ or it is said to be superior if pointing towards the summit of 

 the fniity inferior if pointing towards the base of ih^ fruit. 



• § 15. Accessory Organs, 



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

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

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

 IlookSy Thorns and Prickles^ Jlairs^ and Glands, 



1G9. Tendrils {r-irrJd) are usually abortive petioles, or abortive pedmicles, or some- 

 times abortive cuds of branches. They are simple or more or lesft 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 consis- 

 tence, not branched, and less coiled. 



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

 A Thorn or Spine is the strongly pointed extremity of a branch, or abortive petiole, or 

 abortive peduncle. A Trickle is a sharply pointed excrescence from the epidermisj 

 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 pimgent, 

 they are also cviWod. 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 clotlung) of a plant, in- 

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

 comparison, been termed bristles, hairs, doum, cotton, or wool. 



172. Hairs are often branched. They are said to be attached ly the centre, if 

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

 j[)lumose, if the branches are arranged along a common axis, as in a feather ; stellate^ 

 if several branches radiate liorizoutally. Tliese 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 skin, of an organ, as to its surface and indumentum, is 

 smooth, when without any protuberance whatever. 



glahrous, when without hairs of any kmd. 



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

 mci'cly discoloured. 



furroived (sulcata) or ribbed (costale) when the piU-uUel lines are more distinctly 

 raised. 



