CISTIFLOR^. 



411 



stigma in a groove on the anterior side (Fig. 422 st). Herbs 

 with rhizomes, or annuals ; flowers solitary. V. odorata, canina, etc., have 

 cleistogamic flowers which produce fruit in addition to the large, coloured 

 (violet) flowers. The Pansy (V. tricolor) has large flowers adapted for insect - 

 pollination, and also smaller, less conspicuous ones designed for self-pollina- 

 tion. The stigma, as in Fig. 422 A, st, and B, is situated on the anterior 

 side of the stylar-head, immediately in front of the channel leading down to 

 the spur (sp) ; below it is situated a valve, easily covered with pollen when the 

 proboscis of an insect is introduced into the spur, but which closes upon its 

 withdrawal ; cross-pollination is thus secured. The sweet-scented V. odorata 

 is visited by the honey-bee, which insures cross-pollination, and in the absence 

 of insect visits it effects self-fertilisation by cleistogamic flowers. The con- 

 spicuous but scentless V. tricolor, var. vuJgaris, is less frequently visited by 

 insects (humble-bees). In V. silvatica and V. canina the pollen is carried on 



42i. . 425. 



FIGS. 423-425. Viola tricolor. 



FIG. 423. Capsule after dehiscence (nat. size). FIG. 421. External view of the seed. 



FIG. 425. Seed in longitudinal section. 



the head or proboscis of the honey-sucking bee. The fruits of V. odorata bury 

 themselves slightly in the soil. In the others the fruits are raised above the 

 ground; the 3 boat-shaped valves close together along the central line, and 

 eject the seeds, one by one, with much violence, so that they are thrown to a 

 great distance. 



The Alsodeia-group has regular or almost regular flowers. Gamopetalous 

 corollas are found in Paypayrolece. Sauvagesiea differs the most by its regular 

 corolla, and 5- oo free or united staminodes. 



250 species ; especially in the Tropics. The Zo/u'dmra-species are used as 

 ipecacuanha. A number of FioZa-species are cultivated as garden plants, 

 especially V. odorata (sweet-scented Violet) and V. tricolor, which have a large 

 number of varieties. 



Order 6. Frankeniacese. A small order with doubtful relationships. 

 Perennial herbs or shrubs ; beach plants with nodose stem. Sepals united, 

 petals free. Unilocular ovary, with 3-4 parietal placentas. Fruit a capsule. 

 Embryo straight, endospermous. Especially in S. Europe, Africa, on the 

 shores of the Mediterranean and Atlantic. 



Order 7. Tamaricaceae (Tamarisks). To this order belong only Tamarix 

 and Myricaria. They are shrubs of a cypress- or heather-like appearance, as 



