102 A BIT OF GROUNDSEL. 



found that the crowding of flower-heads on a common stalk is by 

 no means Hmited to the one natural order to which Groundsel 

 belongs, but may be traced through various stages of development 

 in clover, in the umbel of hemlock, in the corymb of the cherry, 

 and in the panicle of grasses. For if we crowd these flowers 

 close together without their stalks, we have an exact representa- 

 tion of the flower-head of the daisy and groundsel. 



To begin with the hoary head of seed-down, whence the name 

 Senecio, from senex, an old man ; each white fibre of this shuttle- 

 cock by which the ripe seed is dispersed by the wind is slightly 

 waved, and has serrated edges (Plate XL, Fig. 4) ; when mois- 

 tened with water, it will be seen, under ^' o.g., to be hollow, and 

 to have a branched tube opening out of each tooth. Before the 

 ovule is fertilised (Plate XI., Fig. i), this down, or pappus, is 

 pressed close to the little yellow corolla, being, in fact, the modi- 

 fied calyx. As soon as fertilisation has occurred (Plate XI., Fig. 

 2), and the ovule begins to swell into a seed, the pappus becomes 

 larger, and the tiny corolla falls out of the middle of the bunch of 

 hairs, which is then ready spread, and floats off with the seed on 

 the first breeze. 



The seed is somewhat oval, and, as the text-books describe it, 

 "ribbed and silky" (Plate XL, Fig. 3). With a i-inch o.g., lon- 

 gitudinal bands of alternate yellow and brown" may be discovered 

 on the seed, the brown portion bearing small, blunt hairs which 

 point upwards, the yellow bands being formed of longer and more 

 slender hairs, lying quite flat when dry (Plate XL, Fig. 5). When 

 wetted with a drop of water, they will rise up, straighten them- 

 selves, and stand out at nearly right angles from the seed. A few 

 globules of oil may be noticed when a portion of a seed is crushed 

 in the field of view. 



The pollen (Plate XL, Fig. 6) is nearly globular, with three 

 principal, and many minute, projections, and will be found a much 

 severer test for the defining powers of an objective than the popu- 

 lar mallow pollen. And the pollen tubes (Plate XL, Fig. 7), 

 which penetrate through the style down to the ovary, and fertilise 

 the ovule or embryo seed, can be found in all stages of growth on 

 almost every stamen. The heads of the Groundsel flowers 

 become conical after fertilisation (Plate XL, Fig. 8). This is 



