Drosera

Drosera is a genus of insectivorous herbs in the Droseraceae or sundew family.

The annuals are glandular, the perennials glandular and deciduous. Geotropic shoots or pseudo-roots bearing reserve food grow into the earth by gravity, becoming swollen and covered by root hairs. There are no true roots. Some species have aerial, rhizome-like stems or tentacles that may be annual or perennial.

Drosera plants have basal leaf rosettes or stem leaves or both. The stem leaves are scattered or alternate. The leaves are simple, bearing various kinds of sticky glandular hairs or trichomes. New leaves start off touching the petioles or with blades rolled inwards. Stipules are present in some species.

The flowers grow on slender or short stalks from the base, from leaf axils or from stem-tips, in cymes or solitary, drooping in bud. The five petals are usually pink, mauve or white, sometimes also red or yellow, some with dark floral bases. The flowers open one at a time in bright sunlight, often for a few hours only and closing at night. The flowers are usually self-pollinating. Petals often remain after withering, forming a covering over the fruit.

There are five stamens. The ovary has three placentas and three styles.

The capsule has three locules, each valved, the calyx persisting around the capsule. The black seeds are ovoid or spindle-shaped.

There are about 80 Drosera species worldwide, most in the southern hemisphere, many in Australia and 20 in southern Africa of which 14 in the fynbos.

Most species grow in moist places where the soil is low in nutrients. The plants absorb nutrients like nitrogen and phosphate from the insects they capture. Droseras use a thick gluey sludge called mucilage attached to the glandular hairs on their leaves for trapping and digesting their prey.

Some droseras have been used in treating coughing and some feature in horticulture.

The plant in picture is Drosera trinervia (Leistner, (Ed.), 2000; Vlok and Schutte-Vlok, 2015; Manning, 2007; Wikipedia).