Euphorbia tenax stems

The cylindrical or terete and spineless stems of Euphorbia tenax, previously E. arceuthobioides, may be grey-green or dull green, during drought yellow-green or purple. They taper notably between base and tip, often branching much, also higher up. Branches are mostly smooth, occasionally showing a rough patch, a laterally compressed tubercle where the ephemeral, deciduous leaves had grown.

This plant was seen in midsummer heat, long after the short-lived triangular leaves on new growth of the last winter had fallen. The rudimentary leaves grow opposite and are sessile or nearly so.

While mature plants have many branched stems, most plants appear few-stemmed and sparsely branched with spiky thin stem tips. In the absence of leaves (which is most of the time), the plant is unable to cast much of a shadow. Branches sprout opposite each other on the stems, well spaced and at right angles to the previous pair (Smith, et al, 2017; Vlok and Schutte-Vlok, 2015; Bond and Goldblatt, 1984; iNaturalist; JSTOR; iSpot).