524 SPARTIUM SPIRJEA 



I inarched it on the single-flowered broom and gave it to Gray and 

 Gordon (two famous nurserymen)." It is still cultivated at Kew, but 

 unless it has deteriorated, it was scarcely worth Collinson's trouble. In 

 the type, the upper edge of the keel towards the base is sensitive. If it be 

 touched by a pencil point (or the proboscis of an insect) the stamens spring 

 out from the keel, sending the pollen in a little cloud. 



SPIR^A. ROSACES. 



This genus includes herbs as well as shrubs, and the latter show every 

 variation in stature from tufted plants a few inches high to those of almost 

 tree-like dimensions such as the new West Chinese S. arborea, which is 

 30 ft. high. Spiraea is the chief genus in a tribe of Rosaceae, and has 

 as it closest allies, Neillia, Exochorda, and Stephanandra all hardy 

 shrubs represented in gardens. I have followed the Bentham and 

 Hooker conception of the genus, which has for so long been adopted 

 in this country, but there is now a disposition to split it up into several 

 genera, as follows : 



SPIR/EA (proper). Capsules free; leaves simple, usually toothed ; -e.g., S. japonica, 

 S. Thunbergi, and numerous others. 



SlBlR^EA. Capsules united at the base ; leaves entire ; e.g. S. Isevigata (the only 

 species). 



SORBARIA. Leaves pinnate ; e.g., S. Aitchisoni, arborea, Lindleyana, sorbifolia. 



CHAM/EBATIARIA. Leaves doubly pinnate ; e.g. S. Millefolium (the only species). 



HOLODISCUS. Fruit an achene containing one seed not splitting to release it as the 

 capsules of the four previous groups do ; e.g. S. discolor. 



Thus, in its more comprehensive sense, Spiraea has simple, pinnate, or 

 bipinnate leaves, all deciduous. The flowers are very uniform in size, 

 varying in most of the species from about J to ^ in. in diameter, but in 

 a few of the finer garden forms like the double-flowered prunifolia and 

 cantoniensis, also in S. Millefolium, they are J in. across. The blossoms 

 are either white or of some shade of red or pink (all the spring-flowering 

 sorts have white flowers), and the inflorescence is either a fascicle or short 

 leafy raceme produced from the buds of the previous year's growths ; or 

 a panicle or corymb terminating the growths of the current season. The 

 petals are normally five, the stamens numerous and often so long as to 

 make a conspicuous feature in the inflorescence, the seed-vessels five, 

 dry, erect, with the style adhering at or near the top, and the calyx 

 persisting at the base. 



The shrubby Spiraeas, of which about sixty species are known, are 

 widely spread over Europe, N. Asia, and N. America, but no shrubby 

 species is a genuine native of Britain, although S. salicifolia has escaped 

 from gardens and become naturalised in various parts of the kingdom. 



As ornaments in the garden, the best of the Spiraeas fill an important 

 place. They flower with great freedom, are often very graceful, and 

 except that some of the earlier flowering kinds are liable to injury by late 

 frost, they are perfectly at home under cultivation. All like a good loamy 

 soil, abundant moisture, and full sunlight. 



PROPAGATION. Many of the Spiraeas spread by means of sucker 

 growths from the base, and such are easily increased by dividing the 

 plants into small pieces. The rest can nearly all be propagated easily 



