THE INFLORESCENCE. 



115 



Fig. 212 . Hypocrate- 

 riform corolla, a, 

 daliate. 



wtieel-shapcd corolla. The tube is greatly elongated at the upper part in the Injpocratt 

 form or salvor-shaped corolla (Fig. 212) ; whilst the injundibuliform, or funnel-shaped 

 corolla, differs from the latter chiefly in having the tube expanded at its upper part. 

 There is yet another form of m< nopelatous corolla, called the labiate, and which offers 

 the greatest resemblance to the 

 inftindihuliform variety. Its dis- 

 tinctive mark is the division of 

 the expanded part into two por- 

 tions, which in some degree re- 

 semble lips (Fig. 210 b], and are so 

 placed that one is called the lower 

 and the other the upper lip. When 

 they are widely separated, as in 

 the dead nettle, the corolla is said 

 to be ringent (Fig. 211), or grin- 

 ning ; and when the upper lip is 

 hollowed and expanded, as in the Monkshood, it is called 

 galeate, or helmet-shaped. When, on the other hand, 

 the lips are pressed closely together, as in the Snap- 

 Fig. 211. Ringent corolla. dragon, the corolla is said to be personate. These ar 

 fanciful terms, but yet in many instances give a 

 familiar idea of the forms to be represented. 



The forms of a polypetalous corolla are perhaps less varied than those now 

 described, and, for the most part, will readily suggest the names by which they are 

 designated. Such, for example, is the cruciate corolla, which is divided into four parts 

 like a Maltese cross, and having six stamens, four of which are long and two short. 

 There is, however, one very marked variety, which offers some complexity, vit., 

 that of the Pea, and many other plants, called the papilionaceous or butterfly- winged 

 corolla (Fig. 213). Such a corolla has also five divisions or petals, four of which are 

 arranged in pairs, and one separately. The pairs form the earina, or keel, a, and im- 

 mediately inclose the sexual organs ; the alee, or wings, 

 b, which lie on either side of the earina; and, lastly, 

 the large vexillum, or standard, c. The two former names 

 are not inappropriate ; but the latter one might have 

 been well exchanged for some term designating a sail. 



The anatomical structure of the corolla differs in no 

 essential respect from that of leaves. There is, however, 

 a greater delicacy of organization, and variation in the 

 relative proportion of parts. Thus, whilst there are 

 stomata as in leaves, they are fewer, and are accom- 

 panied by a smaller quantity of the parenchyma. The 

 veins of the corolla contain a larger proportion of spiral 

 vessels, and less of woody fibre, than is found in leaves. 

 The colours, even the pearl white met with in the corolla, 

 are due to a colouring matter termed chromule (page 53), placed within each individual 

 cell ; and so carefully is this distributed, that adjoining cells may vary considerably 

 in colour. The function of the corolla is that of leaves, with the superadded one of 

 protecting the organs of fructification. 



Fijr.213. Papilionaceous form 

 of corolla. 

 , the earina or keel 



b, the alse or wings. 



c, the vexillum or standard. 



