166 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



outer and two small inner petals (to simplify matters I propose 

 to use this term for all the flower segments) ; stamens often 

 numerous, free or united into a column, anthers obovoid. 

 Female flowers of from two to ten petals. Ovary inferior, 2-4 

 celled ; styles 2-4, with branched twisted stigmas. Fruit a 

 capsule, generally 3 -angled and winged. Seeds very numerous, 

 minute." 



For horticultural purposes the genus may be roughly divided 

 into three groups : — 



1. Species with perennial stems ; example, B. nitida. 



2. Species with a tuberous rootstock, no stem, and ever- 

 green foliage ; example, B. Bex. 



3. Species with a tuberous rootstock and annual stems 

 and leaves ; example, B. Veilchii. 



Before dealing with the cultivated kinds it may be worth 

 while to glance at the most striking features of the genus as a 

 whole, for, although very well defined in its main characters, it 

 exhibits great range of variation in stems, leaves, flowers, and 

 fruits. In the first character, the stem, we have species which 

 form sturdy shrubs, others which send up long bamboo-like 

 stems, copiously branched at the top, others with tall succulent 

 stems which rarely branch ; in B. scandens we have a plant 

 which mimics the Ivy in its habit of climbing and clinging by 

 means of tufts of aerial roots. Then we have the short fleshy- 

 stemmed kinds, such as B. manicata, and the tuberous-rooted 

 with short succulent annual steins or no stems at all. In 

 B. prismatocarpa, a tiny species from Fernando Po, we have a 

 plant with the habit of a Viola in its thin creeping stems and 

 small toothed leaves. 



The variety in the size and form of the foliage is quite 

 extreme. The peltate form is represented by the Lotus-leaved 

 B. uelumbcBfolia and he remarkable B. socotrana, the lance- 

 shaped by B. primulcefolia, and the cut-leaved by B. asple?iiifolia, 

 a native of tropical Africa, with Fern-like foliage. B. verticillata 

 has the leaves in whorls, B. jprolifera produces its flower-scapes 

 from the sinus in the leaf-blade, and so on. In leaf- coloration 

 there are many noteworthy cases, of which the beautiful mark- 

 ings of B. Bex are familiar to everyone. The prettily spotted 

 forms of B. maculata, the sanguineous red of B. sanguinea, and 



