398 



XATUBAL mSTOBY OF PLANTS. 



Medhir solitary, in the rest of the genus grouped into either short 

 nicenies or corymbs, simple or composed of cymes. The different 

 axes of the inllorescence arise from the axils of bracts of successive 



ages 



Cotoneaster thymifoUa. 



CohncaMi',' (lilfers essentially from Pijrus and CratcBgus in the 

 insertion of the carpels. Of these there are five, or more frequently 

 two or three, sometimes only one. They are free from each other, 

 and touch, without adhering, by the ventral angles of their ovaries.^ 

 But the base of each ovary, instead of being horizontal, is sliced ofi' 

 «)l)liquely upwards and outwards, so that there is a broad surface of 

 insertion, applied not towards the bottom of the floral receptacle, 

 but over a large surface of the inside of the sac (fig. 466). Thus, 



the ovary is not very deep at the 

 back, but much deeper on the ven- 

 tral angle. Within, and near the 

 base of this angle, are inserted two 

 collateral descending anatropous 

 ovules, with their micropyles down- 

 wards and outwards.- The styles 

 are free, of the same number as the 

 carpels, either diverging or close 

 together, and each ending in a 

 stigmatiferous head. On the edges 

 of the receptacular sac are inserted the perianth and androceum, 

 and the interval between their insertion and that of the ovaries is 

 lined by a coloured glandular disk. The sepals are quincuncial, 

 the petals imbricated. The stamens are about twenty in number, 

 arranged as in Pi/rus.^ The fruit of Cotoneaster is a drupe consisting 

 of from one to five stones imbedded in a fleshy receptacle.^ In each 

 is an ascending seed, whose exalbuminous embryo has its radicle su- 

 perior. About fifteen species of this genus are known, shrubs or small 



Fig. 166. 

 Longitudinal section of flower. 



' Medik., PJlanz. Geschl., 1793. — Lindl., 

 Trans. Linn. Soc. xiii. 101, t. 9. — DC, 

 Prodr., \\. 632. — Si-ACir, Suit, a Bvffon, il. 

 73.— Endl., Gen., n. 6317.— Pater, Orgauoq., 

 498, t. ccii. figs. 22-34.— 15. H., Gen., 627, n. 

 65. 



' They have two coats. 



' There are, liowever, species with but fifteen 

 stamens, which uniy be arranged in two different 

 *vays, either in tlirees superposed to the petals, 

 and none to the sepals, us in C. tomentosa IjINDL., 



or two stamens superposed to each petal, and 

 one to each sepal. 



* Usually, indeed, this organ, together with 

 the base of the calyx, is the only one to acquire 

 this consistency in the fruit, for the ovaries 

 form little woody nuts, surmounted by the 

 withered style, and present no trace of fleshy 

 tissue above where they project into the sac-like 

 cavity formed by the upper part of the recep- 

 tacle. The stone is thin in C. denticulafa H.B. K. 

 {Nagelia LiNDL., fiot. Eeg. (1845), M/sc, 10). 



