STRUCTURE OF PLANTS. 23 



veins are parallel, like those of endogens. The veins of a leaf are in two 

 strata, the one forming the upper, and the other the under surface ; the 

 former conveying the juices from the stem for elaboration, and the latter 

 returning them when elaborated. Simple leaves have undivided laminae, or 

 laminae divided, but not articulated ; in the latter case it is a compound leaf, 

 as in the Mimosa, and in what would, at first appearance, seem a simple leaf, 

 the Orange. Some leaves have a power of producing leaf-buds, but com- 

 monly not till they have dropped off and lain some time on moist ground, as 

 in Bryophyllum, Malaxis, and some tropical ferns. 



92. Hairs are minute expansions of tissue, found occasionally in all parts 

 of the plant above ground, but chiefly on the under surface, and they are in- 

 tended for the purposes of secretion, for the control of evaporation, and for 

 the protection of the surface on which they are placed. 



93. flower-buds consist of floral envelopes and sexes, and they either pro- 

 ceed from the axilla of common leaves, or from those of bracts or floral 

 leaves. The floral envelopes are connected with the stem by a peduncle. 

 The modes in which flower-buds are arranged on a stem, which are various, 

 are called the forms of inflorescence ; and the order in which they expand is 

 called the order of expansion. 



94. Inflorescence is the ramification of that part of the plant bearing the 

 flowers, and it is in general either terminal, that is, at the end of the branch ; 

 or axillary, proceeding from the axils of the leaves. Both these kinds of inflo- 

 rescence assume a great many different forms which cannot be here detailed. 



95. The floral envelopes consist of the calyx and corolla, both of which are 

 generally present, but sometimes only one, which in that case is considered 

 the calyx ; and sometimes both are wanting, as in apetalous flowers. The 

 divisions of the calyx are called sepals, and those of the corolla petals. 



96. The sexes of plants consist of the male organs, or stamens, and the 

 female organs, or pistillum, with a process, usually an annular elevation, 

 which occurs between them, referred by former botanists to the nectary, but 

 now called the disk. The pistillum occupies the centre of the flower within 

 the stamens, and it consists of three parts, the ovarium, the style, and 

 the stigma. The ovarium is the lowest part, and encloses the ovula or 

 young seeds, in one or more vacuities called cells ; the stigma is the summit 

 of the pistillum, which is connected with the ovarium by the style. This 

 last part is sometimes wanting, but the ovarium and stigma are always 

 present. Those parts of the pistillum which remain, and continue growing 

 after the floral envelopes and the stamens have decayed, are called carpels, 

 which are sometimes united, as in the Poppy, and sometimes separated, as in 

 the Ranunculus. 



97. The ovulum is the infant seed united to the interior of the carpella, by 

 the placenta, to which it is attached by the funiculus, podosperm, or 

 umbilical cord. 



98. The fruit, in a strict botanical sense, is the mature pistillum, but in 

 a less strict sense, it is applied to the pistillum and floral envelopes, taken 

 together and united in one general mass. All fruit, excepting those of the 

 Conifers and Cycadeae, which have no ovarium, indicate upon their surface 

 some traces of a style, and wherever this is the case, what are apparently 

 and commonly called seeds, as the grains of corn and other grasses, are pro- 

 perly fruits. When the pistillum has become mature fruit, what was the 

 ovarium takes the name of pericarpium. 



