ROSACEA. 389 



Later on they separate, and then open longitudinally along the 

 middle line into two thick coriaceous panels to free one or two 

 compressed winged seeds, with membranous edges. The embryo is 

 flattened, fleshy, and exalbuminous, with its radicle superior.' Of 

 the genus Exochorda two species are known,- glabrous shrubs from 

 the north and east of Asia, witli alternate, simple, exstipulate 

 leaves. The flowers are usually polygamo-dioecious ; they come 

 out in the spring in axillary or terminal racemes, each flower axillary 

 to a bract, and with two lateral bractlets near the summit of its 

 pedicel. 



In this group has also been placed JPterostemon^^ on account of its 

 stipulate leaves and exalbuminous seeds, despite its strong analogies 

 with the Saxifragacece. On the edges of its turbinate receptacle are 

 inserted five valvate sepals, as many alternating imbricated petals, 

 and ten stamens superposed to these perianth-leaves. The five 

 superposed to the petals are shorter, with narrow flattened filaments ; 

 the others have broad filaments, divided above into three teeth, of 

 which the middle one bears a cuspidate introrse anther with a dorsal 

 thickened connective. The ovary, lodged in the hollow of the 

 receptacle, is surmounted by a style, dividing above into five trun- 

 cate lobes stigmatiferous at the apex. In the ovary we find five 

 pluriovulate cells ;■* and the fruit, surmounted by the remains of the 

 perianth'^ and androceum, is a five-celled septifragal capsule, con- 

 taining one or more seeds which are ascending, like the ovules, and 

 contain an exalbuminous embryo with its radicle inferior. F. mexica- 

 nus, the only known species of this genus, is a bushy shrub possessing 

 dichotomous branches, and alternate simple petiolate leaves," with two 

 lateral stipules. The flowers are in few-flowered corymbose cymes. 



Eucri/phia' has regular hermaphrodite flowers, usually tetramerous. 



' The radicle is conical, subarcnate. The coty- (Adansonia, is. 149, no. 22), is donbit'nl, for 



ledons are flat on the inside, with convex backs. the single individual studied only possessed inaJo 



Below their insertion each is prolonged into two iiowers. Now, except as regards the gyna'ceutn, 



descending auricles, which touch each other late- Exochorda is undistinguishable from Nuttallia, 



rally, and form a pretty long sheath around the to which genus, therefore, the last species mij^ht 



base of the radicle. perhaps belong. 



^ One is the so-called Spiroia grandijlora •' Sciiauek, Linvcea, xx. 73(!. — 1>. IT., Gen.. 



(Hook., Bot. Mag., t. 1795. — Her., Jlortic. 015, n. 31. — Walp., Ann., i. 2S8. 

 Franc. (18()7), 250, t. viii.). Its flowers are ' There are from four to six ovules inserted 



described as polygamo-dioecious, but we have in the ventral angle of each, 

 found them all hermaphrodite, though it is true '' The petals are withered and rcflexed. 



that our individuals were cultivated, and their <■' They are glandular on the upjier surface, 



vegetation very vigorous. The other species de- downy on the lower, 

 scribed by us under the name oi E.! Davidiana ' Cav., Icon., iv. 19, t. 372. — Cuois., Fiodi: 



