350 



THE HIGHER DICOTYLEDONS. 



The four stamens have long filaments attached to the 

 corolla-tube, while the anthers lie under the hood-like upper 

 lip. The two lower (anterior) stamens cross the upper pair, 

 so that their anthers lie behind and above them. Note the 

 hairy anthers, each with two lobes which, instead of lying side 

 by side, are separated (owing to growth of the connective) 

 and lie in a straight line one above the other. Note the long 

 style which runs up the back of the corolla- tube and is divided 

 at the top into two fine stigmatic lobes. 



Pull off (1) the corolla of a flower, (2) a whole flower, and 

 carefully slit open the corolla-tube. Note the ring of hairs 

 near the bottom of the corolla tube ; the constriction of the 

 tube just below this ring ; the four-lobed ovary with flat 

 upper surface ; the style arising from between the four lobes, 

 which are separated from each other by deep grooves ; the 

 ring-like nectary around the base of the ovary, better de- 

 veloped on the lower than on the upper side (Fig. 142). The 

 ovary consists of two carpels, upper and lower, but early in 

 its development the ovary divides into four parts ; each 

 chamber contains a single ovule. 



The upper lip of the corolla 

 forms a protecting hood over the 

 anthers and style (why is this ad- 

 vantageous?), the lower lip a plat- 

 form for the humble-bees which are 

 the chief visitors to the flowers. The 

 ring of hairs inside the corolla- tube 

 above the ovary stops small in- 

 sects from crawling down to the 

 nectary, besides keeping rain from 

 trickling down and spoiling the 

 honey. The flower is homogamous, 

 and capable of self-pollination, but 

 the forked style- tip hangs down and 

 touches the bee's back before the 

 anthers do, so that cross-pollination 

 occurs regularly. 

 The corolla (with the epipetalous stamens) and the style 

 fall off very soon after pollination has taken place, and 

 the four ovary-chambers grow into smooth black akenes 

 (" nutlets ") with hard coats ; each nutlet is three-sided 



Fig. 143. Floral Diagram of 

 Labiatae. 



