Hemimeris

Hemimeris is a genus of South African endemic, slender annuals in the Scrophulariaceae family. The plants are commonly known as yellowfaces and in Afrikaans as geelgesiggies (little yellow faces).

The single or branched stems are quadrangular (square in cross-section), ridged or channelled, growing in opposite pairs.

The simple leaves are also opposite, although upper leaves in some species may be alternate. Clusters of small leaves are in some species often present in the axils. The leaves of most Hemimeris plants have stalks (petiolate). Leaf-shapes are ovate, obovate or oblong, the margins toothed or lobed.

The flowers grow terminal or axillary and long-stalked, sometimes solitary but usually in a short, stem-tip raceme where the shortened internodes liken the inflorescence to an umbel. The calyx is bell-shaped, its five lance-shaped, slightly unequal lobes usually free to the base.

The yellow corolla is ambiguously two-lipped, hairy on its outside and short-tubed or nearly lacking a tube. The lower lip has a large central lobe with notched tip and concave surface. It also has two small lateral lobes with pouches or spurs near the lip base. Floral oils are produced in these pouches as pollination incentives, collected by certain bees. The small upper lip is one-lobed, exterior in the bud stage with a central pouch and a marginal notch.

The flower has two stamens comprising short, linear filaments, bent at the base and single-celled anthers that converge when mature. Diascia plants, another Scrophulariaceae genus, produce flowers bearing two spurs but four stamens. The superior, usually ovoid ovary of the Hemimeris flower has two locules. It merges into the style that persists.

The fruit is an ovoid or globose capsule. Many black or brown seeds are produced, in some cases they are attached to narrow, membranous wings.

There are four, possibly five species of Hemimeris, all found in the Northern, Western and Eastern Cape.

The plant in picture is Hemimeris racemosa (Leistner, (Ed.), 2000; Vlok and Schutte-Vlok, 2015; Manning, 2007; iNaturalist; http://redlist.sanbi.org).