2024 A TEXTBOOK OF THEORETICAL BOTANY 



In A. cepa var. bulbjferum, the Tree Onion, the flowers are replaced by 

 bulbils, which when mature drop off and reproduce the plant. In most 

 species the flowers (Fig. 196 1) are pollinated by insects and show marked 

 protandry. Nectar is secreted by three double septal glands on the ovary 

 and exudes by canals situated about half-way up. The nectar collects 

 between the base of the ovary and the filaments of the three inner stamens. 

 In A. ursimitn, for example, the inner stamens dehisce first, followed by 

 the outer three, and during this time the style elongates. Insects probing 

 for nectar therefore touch one side of their bodies against an anther and the 

 other against the style. In this way self-pollination is generally prevented. 

 Later should cross-pollination not occur, self-pollination may be achieved 

 by the bending of the style towards an anther. Humble Bees and Hive Bees 

 have both been observed to visit the flowers. In A. cepa the style matures 

 only after the anthers have withered. 



3. Gilliesieae. Rootstock a tunicated bulb. Leaves radical and linear. 



Flowers in a terminal umbel with an involucre of two bracts. 

 Perianth segments usually unequal, free or united into a tube. 

 Stamens varying from six to thirteen, the filaments generally 

 connate. Ovary superior and the fruit a loculicidal capsule. 

 Gilliesia, Trichlora and a number of genera found mainly in Chile, 

 Some species of Gilliesia are cultivated as ornamental flowers. 



4. Galantheae. Rootstock usually bulbous. Stalk rounded bearing a 



few-flowered fasicle of medium-sized, actinomorphic white 

 flowers. Perianth tube absent, stamens all of equal length. 

 Ovary trilocular with numerous ovules in each loculus. 



Fig. 1962. — Galanthus nivalis. Snowdrop. 

 Flowers. 



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