Cassia chamæcrista.
1. Right- and left-handed flowers are produced at the same time on the plant. When several plants are taken, the number of right-and left-handed flowers produced is practically the same.
2. So far as observed, two flowers were never seen open at the same time on a cluster, nor was a bud ready to open the following morning ever found on a cluster with an open flower. Thus, cross-pollination between flowers on the same cluster would not be possible, as it frequently is in S. rostratum.
3. So far as the writers have been able to ascertain, there is no law governing the producing of right-and left-handed flowers on the opposite sides of the main axis.
4. Various species of insects visit the flowers for pollen.
5. It seems that pollination is effected in many cases by the transfusal of pollen from the leg of the insect, where it is being carried, to the stigma of the stamen upon which it is supporting itself. The function suggested by Professor Todd for the incurved petal seems to the writers entirely improbable.
Botanical Laboratory, University of Kansas,
September 28, 1901.
EXPLANATION OF PLATE I.
Fig. 1. Right-handed flower from the front and a little to one side, showing large and small stamens, pistil, and wings of the corolla, which enfold pistil and large stamen in the bud. × 2.
Fig. 2. Tip of a raceme from the front, showing one left- and
two right-handed flowers; also the decurved end of the raceme, with the buds.
Fig. 3. Lateral view of decurved tip of raceme, showing the buds.
Fig. 4. Lateral view of bud ready to open the following morning, showing the two lower lobes of the corolla, enfolding pistil and large stamen.
Fig. 5. Ovary and pistil. × 5.
Figs. 6 and 7. Lateral and dorsal view of large stamen. × 5.
Figs. 8 and 9. Lateral and dorsal view of small stamen. × 5.
Figs. 10 and 11. Hind leg of Bombus, with and without mass of pollen.
