194. 



THE YOUNG 



NATURALIST. 



delion florets, or as thej appear in the 

 double-flowered daisy of tlae gardens. 

 The stamens are always five in number, 

 they are attached internally to the tube 

 of the corolla, they curiously cohere by 

 their anthers into a hollow tube, 

 through which the single style with its 

 forked stigma is pushed. In the 

 florets of many plants in this order the 

 stamens come to maturity before the 

 stigmas, and the anthers, opening on 

 their inner face, the pollen falls into 

 the cavity of the tube, through which 

 it is pushed by the ascending style, 

 where for some little time it lies ex- 

 posed at the opening of the corolla, 

 readily accessible and easily carried 

 away to adjacent florets by every insect 

 visitor. This process may be observed 

 in the central florets, " the eye of the 

 daisy, but it is even more noticeable 

 in those commonly cultivated green- 

 house flowers — cinerarias — in which 

 the corollas are often of a dark purple 

 colour whilst the pollen is of a bright 

 yellow. As if obviously designed to 

 prevent self-fertilisation, the style 

 pushes its way through the anther tube, 

 a solid looking club-shaped body, but 

 when it has surmounted and overtopp- 

 ed the anthers and corolla, having 

 brushed aside its own pollen in its 

 progress, it expands into two forked 

 arms which curl back exposing their 

 inner face which is the stigmatic sur- 

 face, and is readily impregnated with 

 pollen from contiguous flowers. In 



the aggregated multitude of florets, 

 forming the head there is always a 

 succession in the various stages of 

 development, the outer florets will 

 have reached maturity and been ferti- 

 lised before the inner will have become 

 at aU expanded, and hence the head 

 as a whole remains a long time in 

 bloom. 



In Composites there are three very 

 distinct types of flower heads, which 

 are of great assistance in arranging the 

 multitudinous number of species. In 

 the first, of which the thistle is the 

 type, the florets are all tubular and 

 similar. In the second group the florets 

 are also all uniform, but strap-shaped 

 as in the dandehon, whilst in the third 

 or daisy, the two types are combined, 

 for whilst the central florets are all 

 tubular, the outer row are ligulate and 

 expanded into a ray. The daisy is an 

 excellent illustration of the gradual 

 transition and development of organs, 

 showing how change of shape has 

 influenced and determined function. 

 "We have seen that the flower head of 

 this order is a community of individu- 

 als aggregated together for mutual aid 

 and help. We have often insisted 

 upon the benefits and even necessity 

 of the visits of insects to flowers. In 

 this case the individual florets are so 

 small that were they produced singly 

 they might easily be overlooked. So 

 the first obvious advantage of the clus- 

 tered flower head is to render the 



