464 BOTANY 



rather a group of isolated branches, of which the common stock has become 

 extinct. 



The Scitamineae and Gynandrae, the most highly developed of the 

 Monocotyledons, have probably arisen, however, from the Liliiflorae. 

 Many things seem to indicate that the primitive Monocotyledons were 

 grass-like and adapted to wind-pollination ; in particular, the circum- 

 stance that the simplest representatives of several of the orders possess 

 such a form, while the orders Scitamineae and Gynandrae, in which 

 this is not the case, are manifestly of later origin. 



Order 1. Liliiflorae 



Type. — Flower hypo- or epigynous, actinomokphic, rarely slightly 



zygomorphic, always with a perianth consist- 



• ing of complete, fully-developed whorls : P3 + 3, 



A 3 + 3 or A 3, G (3). Ovary three-locular. Ovules 



anatropous or campylotropous, rarely atropous. 



Endosperm always present, enclosing the embryo. 



In the majority of the Liliiflorae, the flowers 



exhibit the typical Monocotyledonous form (Fig. 



400), and are actinomorphic, with five trimerous 



whorls, the members of each whorl being similar. 



The slight zygomorphism displayed by some of 



fig. 400.— Diagram of the j^e f orms j s occasioned by the one-sided curvature 



ji orae . of the stamens. The only essential deviation 



from the Monocotyledonous type is restricted to 



a few families, and consists in the suppression of a whorl of the 



andrcecium. The suppression of single members of the whorls does 



not occur. 



In some genera the whorls are composed, instead of three, of two, four, or five 

 members. These variations are due neither to reduction nor to splitting, and 

 are attributable to differences existing in the very rudiments of the organs. The 

 number of members in the whorls may vary even in the same species, e.g. in Pans 

 quadrifolia, which, in addition to the usual tetramerous flowers, not unfrequently 

 produces others constructed on the plan of five or six. 



The Liliiflorae are, with few exceptions, herbs, in which the sub- 

 terranean parts often take the form of perennial rhizomes or bulbs, 

 while the aerial shoots usually die after the ripening of the seeds. In 

 only the simplest, apparently oldest, grass-like forms are the flowers 

 inconspicuous and adapted to wind-pollination ; otherwise they are 

 large, beautifully coloured, solitary or aggregated into loose inflor- 

 escences. 



The differences between the families are not uniformly constant ; on the con- 

 trary, in some of the species of almost every family, characteristics distinctive of 

 other families occur, e.g. three stamens in families in which six is the normal 



