GROUP IV. — PHANEROGAMIA : ANGIOSL'ERMj;. 



15 



limb, as in the Pink (Fig. 330 A B). The Corona (paracorolla) in 

 the Narcissus and Lychnis is formed by ligular outgrowths from 

 the claws (Fig. 330 B I). Any segmentation of the petal, as in 

 the Pink (Fig. 330 A) is unusual ; emarginate or obcordate petals 

 are more common. In many cases the petals have spur-shaped 

 appendages (Violet, p. 511), or they are prolonged at the base into 

 tubes, as in Hellebortis and Aconitum. This peculiarity is con- 

 nected with the secretion of the nectar (page 526). 



The Reproductive Organs of the Floiuer are sporangia of two 

 kinds, microsporangia and macrosporangia, borne usually on 

 sporophylls, though sometimes directly on the floral axis. The 

 flower is usually ambisporangiate ( ^ , hermaphrodite, see p. 432) ; 

 but it is not infrequently monosporangiate (unisexual), in which 

 case the flowers are either microsporangiate ( <^ , stamina!) or 



Fig. 330.—^ Petal of IHnnthut superhus, with (n) the claw and (i>) the limb, much divided. 

 B Petal of Lychnis : n claw ; p limb ; I ligula. C Flower of Potentilla, seen from below : 

 c corolla ; k calyx; a epicalyx. 



raacrosporangiate ( ? , carpellary). The plants which have mono- 

 sporangiate flowers may be either monoecious (e.g. Zostera, Arum, 

 Cai*ex, Typhacea?, Zea, BetulaceaB, Euphorbia, Buxus, Juglans, 

 Quercus, etc.): or dioecious (e.g. Pandanaceae, some Palms, Naias, 

 Vallisneria, Hippophae, Cannabinaceae, Salicaceae, Mercurialia, 

 Viscum, Empetrum, Feuillea, etc.) : or polygamous. Of polygamy 

 there are several varieties : thus, the plant may bear ambi- 

 sporangiate flowers and staminate flowei's (e.g. Veratrum, Ptelea, 

 ^sculus Hippoca^tanuniy Celtis) ; or ambisporangiate flowers and 

 carpellary flowers (e.g. Thymus vulgaris and T. Serpyllum, Parie- 

 tana diffusa and P. officinalis) : or it bears ambisporangiate flowers 

 and both staminate and carpellary flowers (e.g. Fraxinus excelsior^ 

 Sapon aria ocy m oides) . 



