Roella

Roella is a genus of summer-flowering undershrubs, rarely herbs forming part of the Campanulaceae or bellflower family.

The small, alternate leaves are linear or ovate and sessile, somewhat ericoid, often recurved, rarely incurved. The leaves next to the flowers at stem-tips are sometimes pinnately spine-lobed. Small leaf clusters may grow from older leaf axils.

The stalkless stem-tip flowers are solitary or in groups. The mostly five-lobed calyces with shallow, saucer-shaped tubes are longer than the corolla tubes. The corollas have bell-shaped tubes at the base, mostly ending in five elliptic or oblong, spreading lobes. The petals are white, blue in several sometimes very pale shades, sometimes with darker spots or rings on the inside of the lobe bases, very rarely yellow or red. Where calyces and corollas are not five-lobed, they have four lobes. The disc below the flower is swollen, sometimes like an annulus, a ring-like structure.

There are mostly five (sometimes four) stamens, free and growing from the base of the corolla tube, mostly included up to slightly exserted. The filaments are expanded low down into oblong, ciliate, scaled structures over the nectar bearing discs. The linear anthers attach at the base to the tips of the filaments. The two-chambered ovaries are inferior with many ovules in each chamber or locule. The rod-like style is simple, the fleshy stigma two-lobed and variable with two glands at its base. Flowering mostly happens in the first few years after fire.

The fruit is a two-locule capsule, dehiscing when ripe through a hole in the top with apparent lid, the persistent calyx, and no valves present. Numerous thick, angled seeds are produced.

There are about 20 Roella species, all in South Africa, most in the Western Cape, one in the Eastern Cape and one in KwaZulu-Natal.

The plant in picture is Roella incurva (Leistner, (Ed.), 2000; Manning, 2009; Pooley, 1998; https://pza.sanbi.org).