380 



VARIOUS PLANT GROUPS 



Fig. 299, I. — Flower of Oxcye 

 (Heliopsis scabra, Sunflower 

 Family, Composite). A~N, 

 stages in the development of 

 a tubular floret, enlarged. A, 

 very young stage in which 

 the' flower [fl) is as yet with- 

 out petals but is plainly dis- 

 tinguishable from its bract 

 (6). B, shows the ringlike 

 swelling (A:) which represents 

 the calyx, and five knobs (c) 

 which are the beginnings of 

 petals. C, a somewhat more 

 advanced stage, just before 

 the appearance of stamens. 

 Z), showing the stamens (a) 

 just appearing. E, same 

 stage as D, cut vertically. 

 F, later stage in which the 

 beginnings of two carpels {g) 

 appear. G, same stage, 

 viewed from the side, show- 

 ing that the petals or corolla 

 lobes have curved inward 

 protectively and are united 

 below by a ring of tissue 

 which by upward growth be- 

 comes the corolla-tube bear- 

 ing the five lobes above. H, 

 same stage, cut vertically; 

 showing the upward growth 

 of the carpels i,g) leaving a 

 hollow in the stem-tip (torus). 

 J, later stage, cut vertically 

 through the middle of the 

 carpels (g) showing a deepen- 

 ing of the hollow in the torus. 

 K, bud of middle age, show- 

 ing the corolla-tube (c) with 

 its five lobes well developed, 

 and lower part of the pistil 

 (g), enveloped by the torus, 

 becoming plainly distinct as 

 an "inferior ovary." L, a 

 somewhat later stage, cut ver- 

 tically, showing the appear- 

 ance of two styles (s) , still dis- 

 tinct, and a young ovule (o) 

 with its outer coat half-grown. M, bud almost ready to open; the two 

 styles having grown into one (s); the anthers (a) joined into a tube; 

 the sepals (k) distinct prominences on the top of the torus, a nectar- 

 gland (d) ; and the ovule (o) completely formed. -V, Tubular floret, 

 open, showing anther-tube (a), corolla-tube (c), and inferior ovary (g). 

 OS, stages in the growth of a ray-floret. O, very early stage in which 

 five petal-lobes appear, three of which, however, are distinctly larger 

 than the other two. P, later stage in which the three larger lobes (c) 

 have become much larger, while the two smaller ones have remained 

 undeveloped. Q, ray-floret about half-grown, showing two of the 

 three petal-lobes separate to the base. R, same, cut vertically between 

 the two separate petals, showing the union of the middle one (at the 



