1250 A TEXTBOOK OF THEORETICAL BOTANY 



3. Secretion in the spur in Tropaeoliim. This 

 spur appears to be attached to the 

 posterior sepal but developmentally it 

 seems to belong to the receptacle, so 

 that its status is doubtful (cf. Pelar- 

 gonium). 



(b) Nectar is secreted by the petal surfaces. 



Examples: i. Nectar exudes in small droplets from the 



stomata of the large anterior petal in 

 Verbascum. 



2. Nectar exudes in small droplets from 



inside the lower part of the tubular 

 corolla and collects into a large drop, 

 in Lonicera, Pyrola, Narcissus and Iris. 



3. The whole adaxial surface of the petal is 



secretory in Feijoa (Myrtaceae). 



[c) Nectar is secreted in grooves, pouches or spurs. 



Examples: i. Each perianth part has a longitudinal 



channel filled with nectar in Lilium, or 

 on the labellum only, in some Orchids. 



2. There is a secretory thickening on the 



petals, continued downwards into a 

 groove in Rhododendron. 



3. Nectar is formed in spurs in many Orchids, 



in Valeriana and in Viola, Linaria and 

 Aquilegia. 



4. Nectar is formed in pouches on the 



perianth parts, uncovered in Fritillaria 

 but covered by a flap in Ranunculus. 

 In Garidella (Nigella) the pouch is 

 formed at the junction of the limb and 

 claw of the petal. 



5. Nectar is secreted in sacs or tubes formed 



by the modification of entire petals or 

 possibly of stamens, in many Ranun- 

 culaceae, e.g., Helleborus, Trollius and 

 Nigella, and in Epimedium in Berbe- 

 ridaceae. These structures are often 

 called " honey leaves " and they may 

 be of quite complex structure. 



The histological structure of floral nectaries is very varied, even within 

 the limits of a single genus such as Iris. Generally speaking the tissue 

 consists of small-celled parenchyma, both with and without air spaces, and 

 there is usually a vascular supply in close relation to the nectary, frequently 



