APPENDIX A 649 



frequently female, or neuter. A third type is the ligtdaie floret, in which the 

 corolla is split on one side, and all the five petals, as shown by the five distal 

 teeth, are elongated into a strap-shaped ray ; but here all five join in its 

 formation (Fig. 502). According to the type of flower the Family is divided 

 into two Sub-families : (i) The Tubuliflorae, in which the flowers are all tubular, 

 or the outer may be developed as ray-florets (Fig. 500). They have watery 

 juice. Examples are the Groundsel, Daisy, Sunflower, and Cornflower, 

 (ii) The Lignliflorae, in which all the flowers are ligulate (Fig. 502). They 

 have milky juice. Examples are Dandelion or Hawk-weed. 



(i) Tubuliflorae. 



(42) The Common Groundsel (Senecio vulgaris, L.) is one of the commonest 

 weeds of cultivated ground. It is annual and herbaceous, with branched 

 leafy stem, bearing a few heads drooping when young, erect when old. 

 The single head, examined in full flower, shows a green involucre of bracts, the 

 outer short, the inner long, with black tips. These surround numerous 

 tubular disc-florets. Ray-florets are usually absent. The single disc-floret 

 consists of : 



Calyx, replaced by numerous bristles (pappus), rising from the top of the 

 inferior ovary. 



Corolla, petals 5, gamopetalous, superior, rather longer than the pappus. 

 The five equal teeth are borne at the end of the corolla-tube, which is narrower 

 below and widens upwards into a bell. 



Androecium, stamens 5, epipetalous, alternating with the petals, inserted 

 by five distinct filaments on the throat of the corolla-tube at the point where 

 it dilates. Anthers united into a tube (syngenesious). 



Gynoecium, carpels 2, syncarpous, ovary inferior, unilocular, with one 

 ascending, anatropous ovule. Style elongated, bearing in fully matured 

 flowers two antero-posterior lobes, which diverge beyond the tube of the 

 anthers. 



Fruit, a brown striated nut, bearing the wide-spread pappus at the tip, 

 by means of which it is distributed by the wind. 



Pollination. If several flowering heads be examined from above it will be 

 seen that the flowers mature in acropetal succession, the oldest being outside. 

 The corolla bursts, the syngenesious and introrse anthers protrude, and the 

 pollen is driven out of them by the elongating style, the stigmatic lobes being 

 still appressed ; later these expand, exposing their inner receptive surfaces. 

 The flowers are thus protandrous. There is honey-secretion in the corolla- 

 tube, but the flowers are rarely visited by insects and self-pollination is 

 certainly common. 



(43) The Ox-Eye Daisy {Chrysanthemum Leucanthemum, L.), belonging 

 also to the Tubuliflorae, is a common perennial of dry ground (Fig. 500). The 

 capitulum is solitary on the end of a stem, which widens out to form the general 

 receptacle. From its margin arises the involucre of bracts, with membranous 

 margins. Within are numerous florets inserted on the receptacle, but without 

 any bracts subtending them. Centrally are the yellow florets of the disc, 

 peripherally the white ray-florets. Each disc-floret consists of : 



Calyx, represented only by a rim round the upper limit of the inferior 

 ovary. There is no pappus. 



