ROSACEA. 467 



ing ; micropyle superior extrorse. Fruit ? . . . . — A slirub ; branches 

 crowded spreading, often spinescent in last ramifications ; leaves 

 alternate simple, crowded towards summit of twigs; flowers soli- 

 tary terminal, bracteolate at base. [California^ See p. 372. 



23. Adenostoma Hook. & Arn, — Flowers hermaphrodite ; re- 

 ceptacle tubular or obconical 10-ribbed, lined by a glandular disk 

 with its free edge thickened. Sepals 5, inserted in throat, imbri- 

 cate. Petals 5, alternating imbricate. Stamens co (7-20) ; 

 filaments free (of the Rosacea) ; anthers introrse, dehiscing longi- 

 tudinally ; connective thickened. Cairpel 1 (of Purshia) ; ovary at 

 apex unequally gibbous pilose ; style subterminal, geniculate, apex 

 capitate stigmatiferous ; ovules 1, 2, ventral descending ; micropyle 

 superior extrorse. Achene coriaceous, included in hardened recep- 

 tacle. Seed ? . . . . — Rigid shrubs ; branches straight divaricating ; 

 leaves heath-like or fascicled entire ; stipules minute lateral ; flowers 

 in multibracteate glomeruli, axillary to the leaves or the bracts of a 

 compound spike. {California^ See p. 373. 



IV. SPIREEiE. 



24. Spiraea T. — Flowers hermaphrodite or polygamous ; recep- 

 tacle concave, shortly campanulate or urceolate. Sepals 4-6, usually 

 5 ; prsefloration imbricate or valvate. Petals as many, inserted 

 in throat of receptacle, imbricated or contorted. Stamens 

 20-GO (of the Rosacece) ; filaments free or connate at base, in- 

 serted in tliroat of receptacle either on 5-1 0-lobed margin or 

 inner surface of glandular disk lining receptacle. Carpels 

 usually 5, oppositipetalous or more rarely alternipetalous, more 

 rarely 1-4 or more, free or connate to a variable height, in- 

 serted in bottom of receptacle; styles terminal or subterminal, 

 straight or geniculate ; apex truncate stigmatiferous ; ovules 2-oo , 

 2-seriate inserted on ventral angle, transverse or descending, more 

 rarely ascending. Fruit of 1-xi achenes follicles or legumes, free 

 or connate, straight or more rarely contorted. Seeds l-oo , descend- 

 ing, usually linear thin ; integuments membranous or marginate, 

 subulate ; embryo fleshy exalbuminous ; radicle usually superior. — 

 Shrubs or undershrubs, more rarely herbs ; leaves alternate simple 

 digitate pinnate or decompound ; stipules lateral free or adnate to 



