522 



PART IV. CLASSIFICATION. 



grow up around the ovary. The succulent mesocarp is thin, and ruptures 

 irregularly; the hard endocarp opens on germination along the line of 

 junction of the two carpels, and then the incurved margins of the carpels 

 are seen as an incomplete longitudinal septum projecting between the two 

 cotj-ledons of the embryo which is closely invested by the endocarp. J. 

 regia, the Walnut Tree, is a native of Southern Europe : in North America, 

 J. cinerea and niyra occur ; also various species of Carya, the Hickory, re- 

 markable for its very hard wood. 



Order 5. SALICACILE. The dioecious flowers are arranged in 

 amenta, and are borne in the axils of the bracts without any 

 bracteoles. There is no perianth, but each flower contains a 

 glandular disc or nectary. The ovary is dimerous and unilocular, 

 and contains a number of parietal ovules. The dehiscence of the 

 fruit is loculicidal ; the numerous seeds are furnished with a pencil 

 of silky hairs at their bases (p. 416). The catkins are developed at 



the ends of lateral dwarf- 

 shoots which always bear 

 scales or even a few 

 foliage-leaves. 



Salix, the Willow or Sal- 

 low, has entire bracts, a one- 

 or two-toothed nectary in 

 each flower, and usually 

 two stamens, entire shortly- 

 stalked leaves, and its win- 

 ter-buds are covered by a 

 scale which is formed by 

 the coalescence of two. Some species, such as S. alba, fragilis, and babylonica , 

 the Weeping Willow, have pendulous branches, and are arborescent : most 

 of them are shrubby, and some, such as S. reticulata, retusa, and herbacea, 

 are small decumbent shrubs occurring in the Alps and in high latitudes. 

 In S. purpurea and incana the two stamens are connate: S. triandra has 

 three stamens. Most of the species grow on the banks of rivers ; S. aurita 

 and caprea in forests, and S. repens and others on moors. 



Populus, the Poplar, has toothed or lobed bracts, a cup-shaped nectary 

 (Fig. 335 C, p), and numerous (4-30) stamens ; the leaves are often lobed and 

 have long petioles ; the winter-buds are enclosed by a number of scales ; 

 the shoots have a terminal bud. 



Cohort III. Chenopodiales. Flowers usually monoclinous ; 

 perianth sepaloid or petaloid : ovary monomerous or polymerous ; 

 ovule usually solitary ; embryo coiled or curved. 



Order 1. CHEXOPODIACEJE. Flowers small, united to form a 

 dense inflorescence : the bracteoles are frequently suppressed. 



Fig. 335.- 4 s , B ? flower of Salix -. d bract; h disc ; 

 o stamens; /ovary; n stigmata (enlarged). C De- 

 hiscent fruit of the Poplar ;s seeds : p disc. 



