This family of plants possesses seed-vessels which remain firmly shut on their contents while the soil is hot and dry, and thus preserve the vegetative power intact during the highest heat of the torrid sun; but when rain falls, the seed-vessel opens and sheds its contents just when there is the greatest probability of their vegetating.

In other plants heat and drought cause the seed-vessels to burst and shed their charge.
One of this family is edible ('Mesembryanthemum edule'); another possesses a tuberous root, which may be eaten raw; and all are furnished with thick, fleshy leaves, having pores capable of imbibing and retaining moisture from a very dry atmosphere and soil, so that, if a leaf is broken during a period of the greatest drought, it shows abundant circulating sap.

The plants of this family are found much farther north, but the great abundance of the grasses prevents them from making any show.

There, however, they stand ready to fill up any gap which may occur in the present prevailing vegetation; and should the grasses disappear, animal life would not necessarily be destroyed, because a reserve supply, equivalent to a fresh act of creative power, has been provided.
One of this family, 'M.

turbiniforme', is so colored as to blend in well with the hue of the soil and stones around it; and a 'gryllus' of the same color feeds on it.