Part 132. The morning-glory family (Convolvulaceae) is well exemplified by the sweet potato (Figs. 56, 57).

Formulas of Ipomoea and Convolvulaceae are given on pages 416, 417.

The new features to be noted here are the aestivation of the corolla and the dehiscence of the capsule. So complete is the coalescence of the petals in most members of the family and so flaring the corolla, that as it forms in the bud it becomes folded or plicate,1 and the folds overlap in a convolute manner. Such aestivation may be described as plicate-convolute. The capsule of the morning-glory (of which the sweet potato is one species) differs from the other capsules we have studied in having the valves separate not only from one another but from the partitions within, the sutures coming at the margin of the partitions. Dehiscence of this type is termed marginicidally septifragal.2

1 Pli'cate - L. plicatus, folded into plaits. P v.

2 Sep-tif'ra-gal - L. septum, partition; frangere, break. C/ -p.

The family is a small one made up mostly of round-stemmed herbaceous vines, with more or less milky juice; alternate, ex-stipulate leaves; regular flowers having a gamopetalous corolla, plicate-convolute in the bud, and having usually adherent stamens, the ovary being two to five-celled; and with the fruit, commonly a capsule, containing a few large albuminous seeds with folded embryo.