Note 22: Key to Tetradenia in Zimbabwe and Mozambique by Bart Wursten

This is a key to the species of Tetradenia which occur in Zimbabwe and Mozambique. It has been extracted from the paper, Tetradenia (Lamiaceae) in Africa: new species and new combinations by P.B. Phillipson and C.F. Steyn (2008).

1. Leaves strongly discolorous with the entire lower surface and the veins obscured by a dense white woolly indument; young stems and inflorescence branches sometimes with a dense brown woolly indument ... 2

— Leaves not or at most slightly discolorous, the lower surface and the veins variously pubescent, but the indument of fully expanded leaves never completely obscuring the surface or the veins; stems and inflorescence branches variously pubescent, but never with a dense brown woolly indument ... 3

2. Leaves triangular to ovate or cordiform usually with pointed marginal teeth; young stems and inflorescence branches with a dense brown woolly indument; both male and female spikes dense; corolla tube of the male flowers ± 1.0 mm long; from the Ubombo Mountains in the extreme north of KwaZulu in South Africa, Swaziland, the northern provinces of South Africa, eastern Zimbabwe and adjacent parts of Mozambique ... 1. T. bainesii

— Leaves ovate to elliptic with rounded marginal teeth; stems finely hispid, somewhat glabrescent; inflorescence branches with a pale villous indument; male spikes lax, female spikes dense; corolla tube of the male flowers 1.5-2.0 mm; Malawi, Zambia, southwestern Tanzania, southeastern Democratic Republic of the Congo, and Zimbabwe ... 4. T. discolor

3. Small rather weak shrub (1-2 m tall) with small leaves (blades often < 20 × 15 mm); inflorescence a small rather irregular cylindrical panicle or somewhat reduced to separate lateral partial inflorescences or even solitary spikes; male and female spikes often < 3 cm long; northern provinces of South Africa, eastern Botswana, central Namibia and the Matopo hills in southwestern Zimbabwe ... 3. T. brevispicata

— Large vigorous shrub (often over 2 m tall) with large leaves (blades usually > 3 cm long); the longest male spikes > 3 cm long (the female sometimes shorter); widespread, but not known from Botswana, Namibia or the Matopo hills in Zimbabwe ... 4

4. Male flowers funnel to trumpet-shaped, corolla c. 2.7 mm long from the base of the tube to the tip of the bottom lip, the tube expanding gradually from the base, pedicels of male flowers ± 0.3 mm long; stems hispid and ± equal mixture of glandular and eglandular trichomes; petioles ± 1/3 as long as the blades; widespread from Swaziland northwards to southern Tanzania, and west to Namibia and Angola ... 5. T. galpinii

— Male flowers broadly funnel-shaped, corolla c. 3.4 mm long from the base of the tube to the tip of the bottom lip, the tube expanding abruptly beyond the calyx mouth, pedicels of male flowers > 0.7 mm long; stems hispid with mainly glandular trichomes; petioles ± 1/2 as long as the blades; from KwaZulu-Natal in South Africa, through Swaziland, southern Mozambique and eastern Zimbabwe to southern Malawi ... 8. T. riparia