50 



THE GARDENER'S ASSISTANT. 



Fig. 58.— Campanula Flower, 

 showing a regular flower 

 with five- parted calyx 

 and corolla. The leaf on 

 the pedicel is called a 



is then called monoecious. In other instances the 

 male flowers occur in one individual, the female 

 in another, as in the Willows. Under such cir- 

 cumstances the plant is spoken of as dioecious. 



From what has been said it is clear that the 

 essential parts of a flower are the stamens and 

 the ovules respectively, and that these alone are 

 absolutely requisite. But in most cases we find 

 other parts added for the sake of protection, or 

 with the object of promoting and facilitating 

 fertilization in some cases, and of obstructing it 

 in others. Botanists speak of complete flowers 

 and of incomplete flowers. A complete flower is 

 one which possesses (1) a 

 receptacle or thalamus; (2) a 

 calyx; (3) a corolla; (4) one 

 or more stamens; (5) one or 

 more ovaries containing 

 ovules. An "incomplete" 

 flower is one in which some 

 of the parts just mentioned 

 are deficient. A " regular " 

 flower is one in which the 

 parts of each whorl are 

 nearly or quite equal in size 

 and alike in form, as in 

 a tulip. An ''irregular", 

 sometimes called zygomor- 

 phk, flower, such as that of 

 an Orchid, is one in which some of the parts of 

 a whorl differ from the rest in size and form. 



Speaking broadly, the parts of the flower 

 originate like leaves, and are arranged in the j 

 same manner, generally in whorls, one whorl 

 alternating with or coming between two other i 

 whorls. If the parts are very numerous, then I 

 they are usually arranged in a spiral manner, as 

 may be seen in the "pips" of a strawberry. The 

 parts of a flower may be all distinct and separate, 

 or they may be partially, and to a very different 

 extent in different cases, " inseparate ". In the 

 latter case the parts are said to be united, 

 though in reality they have never been other- 

 wise than whole. "Union" of this character, 

 if between parts of the same whorl, is said to 

 be cohesion. If the union, or more correctly 

 the lack of separation, be between two whorls, 

 the term adhesion is made use of. Concrescence 

 is a term which includes both forms of apparent 

 union. Coming now more particularly to the 

 parts of a complete flower, as above defined, 

 we have first to consider: 



1. The Receptacle or Thalamus. — This is 

 merely the extreme end of the flower-stalk. It 

 is, therefore, the extremity of a branch or axis 

 from whose sides are given off in regular order 



the modified leaves which constitute the parts of 

 the flower. The thalamus is usually not so con- 

 spicuous as to merit special attention, but in some 

 cases it is greatly developed; thus, in the Rose 

 Hip, the Apple, or the Pear, it swells out into a 

 vase-like form and constitutes what in popular 



Fig. 59.— Strawberry— with Section, showing thickened receptacle 

 bearing the true fruits or pips on the surface. 



but inaccurate language is called the fruit. In 

 other cases, it is prolonged above the flower, as 

 in the ripened Strawberry, which, with like 

 technical inaccuracy, is termed the fruit (fig. 59). 



2. The Calyx. — This is the outermost of the 

 two coverings by which the stamens in a com- 

 plete flower are enveloped. It consists of a 

 number of pieces which receive the name of 

 sepals. They are usually of a green colour 

 like the leaves, which they also resemble in form, 

 but are less highly developed. They are free, 

 when the calyx is called polysepalous, as in a 

 Buttercup ; or they may be partially inseparate, 

 when the calyx is called gamosepalous, as in a 

 Gardenia. In the latter case the lower part of 

 the calyx forms a tube, as in a Fuchsia, whilst 

 the free portions collectively form the limb. 



The office of the calyx is mostly to protect 

 and shield the more important parts within from 

 undue radiation or the direct effects of wet. 

 Sometimes, as when invested with prickles or 

 sticky hairs, it prevents the entrance of undesir- 

 able visitants. 



3. The Corolla, Perianth. — Within the 

 calyx and between it and the stamens in a com- 

 plete flower is a whorl of 

 pieces which are called petals. 

 They alternate with, or 

 come between the sepals, 

 and are usually of some 

 other colour than green, 

 and are, therefore, in so 

 far, less like leaves than 

 the sepals. Petals may be 



Fig . eo.-strawberry Flower, free, when the flower, as 

 in the Rose or Strawberry, 

 is said to be polypetalous (fig. 60); or inseparate, 

 w T hen it is called gamopetalous, as in a Primrose. 

 In that case the corolla has a tube and a limb, as 

 the calyx has under like circumstances. The 



