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A TEXTBOOK OF THEORETICAL BOTANY 



In the classification of the family the number and arrangement of the 

 flowers is one of the chief characteristics for distributing the genera. The 

 following is based upon the system proposed by Pax. 



I. Crocoideae 



Plants small and growing from corms. Flowers terminal with occa- 

 sionally additional axillary flowers. Spathe one-flowered. Flowers 

 actinomorphic. Perianth segments equal. Leaves linear arranged 

 approximately in two ranks. Crocus and Romulea. 



The genus Crof//^ (Fig. 1971) has about eighty species which are parti- 

 cularly common in the mountains of southern Europe and in western Asia 

 and Asia Minor. Four are naturalized in Britain. The corm is covered with 

 dry scale leaves in whose axils may arise one or more buds, giving rise to new 



Fig. 1971. — Crocus siebeii. P.ntire flowering 

 plant with corm. 



corms on the top of the old. The leaves are dorsiventral and variously 

 grooved on the back. The flowers may be developed in small cymes but are 

 more often terminal and solitary. The flowers close up at night as a result 

 of the lowering of temperature. The perianth is often brightly coloured 

 and the tube is very long, and passes down below the soil. At its base lies 

 the ovary, which is thus protected below the ground. 



The flowers are protandrous and are visited by bees, butterflies and 

 moths. Nectar is secreted by the ovary and the anthers dehisce outwards. 

 An insect forcing its way down to the nectar therefore first touches these 

 anthers. A visit later to a more mature flower will ensure cross-pollination 



