THE STnUCTUEE OF PLANTS. 



11 



and stigma being the essential portions, tlie style may ba, and frequently 

 is, wanting, when the stigma is sessile. The ovary contains within it 

 the rudiments of seeds or Oru/es, which are, after they have received the 

 fertilizing influence of the pollen which is communicated through the 

 stigma, developed into seeds. The number of pistils in a flower is ex- 

 pressed by prefixing the greek numerals to gynous ; a monogynous one 

 having one pistil ; a di gynous one having two pistils, &c. For farther 

 in relation to the structure of the pistil, see 45, 



38. The stamens and pistils being the essential parts of the flower, 

 one or both series of the floral envelopes may be wanting : when one of 

 the series is absent, it is the corolla, and the flower is then apetalous 

 (without petals) ; or when both are absent, the flower is naked. 



A complete flower has all four series of organs present : if either of 

 these is lacking it is then incomplete. An incomplete flower may pro- 

 duce seeds, having both stamens and pistils, and as long as these are 

 both present, the flower is perfect. If either of these is absent, the flower 

 is impel fe t. These organs are frequently produced in separate flowers 

 (Figs. 69 and TO) : when the staminate and pistillate flowers are both 

 borne on the same plant, they are said to be monoEcious (i. e. in one 

 household) ; or if produced on different plants, dioecious (in two house- 

 holds). AVhen some of the flowers are perfect and the others separated, 

 they are polygamous. Flowers having the different series of organs with 

 the same number of parts in each, ave symmetrical ; those having the 

 par'cs in each series of the same shape, are regular ; or of different shapes, 

 irrjgular (Fig. 13). 



39. The infinite variety of forms which flowers present is produced by 

 modifications in these four series of parts. Some parts of a set may be 

 wanting or much changed from the usual form, or the number of parts 

 may be multiplied. The different parts of a set may unite and form one 

 piece, or the structure may be st 11 farther varied by the cohering or 

 growing together of the parts of two or more adjoining series. 



It is very common to find the sepals of a calyx or the petals of 

 a corolla more or less joined by their contiguous edges so as to form a 

 tube. When the sepals are distinct, the calyx is polysepalous ; and 

 where united, monosepalous. Where the union is only partial and the 

 upper portions of the sepals free, it is sometimes convenient to say that 

 it is cleft or parted as the case may be. 



If the corolla has distinct petals, it i: polypctalous ; when these are 

 more or less joined, monopetalous or gamopetalous. In a monopetalous 

 corolla the parts are not usually united for their whole length : — tlie 

 free or expanded portion is the Limb and the narrower portion the Tube. 

 Among the forms of monopetalous corollas may be mentioned the follow- 

 ing : the funnel-shaped or rnfundibuliform, when the tube is narrower 

 below but spreads at summit (Fig. 167) ; the hell-shaped or campanu- 

 late, with a rounded base and open or spreading border ; tubidar, 

 when elongated and more or less cylindrical throughout (Fig. 115) ; 

 salver-shaped, when the tube is very narrow and bears a broad spreading 

 limb ; and wheel-shaped or rotate, with a broad limb and scarcely anv 



