Tetradenia Benth.

Phillipson, Peter B. & Steyn, Catherine F., 2008, Tetradenia (Lamiaceae) in Africa: new species and new combinations, Adansonia (3) 30 (1), pp. 177-196 : 179-181

Genus Tetradenia Benth.

Edwards’s Botanical Register 15: t. 1300 (1830), non

Nees 1831. — Type: Tetradenia fruticosa Benth.

Iboza N.E.Br. in Thiselton-Dyer (ed.), Flora Capensis 5 (1): 298 (1910). — Type: Iboza riparia (Hochst.) N.E.Br.

IDENTIFICATION KEY TO TETRADENIA BENTH. IN AFRICA

1. Plants hermaphrodite, bearing bisexual flowers; inflorescence consisting of a long largely unbranched terminal spike; Eastern Cape Province of South Africa......... 2. T. barberae

— Plants dioecious, or in some species occasional hermaphrodite individuals bearing bisexual flowers may be present; inflorescence a branched terminal panicle-like thyrse; throughout much of tropical Africa, extending into KwaZulu-Natal and Northern provinces of South Africa......................................................................................................................... 2

2. Calyx lobes subequal, the lobes all acute and with the upper lobe gradually spreading in fruit; inflorescence large but poorly branched; female with long lax spikes, the terminal usually> 8 cm long; highlands of Ethiopia............................................ 7. T. multiflora

— Calyx lobes unequal, the upper lobe large, rounded, abruptly bent upwards in fruit, the lateral and lower lobes small, acute, separated by a deep basal; inflorescence large and well-branched or highly reduced; female with short dense spikes, the terminal usually <3 cm long; widespread (including Ethiopia) ............................................................ 3

3. 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 ............................................................................................. 4

— 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 ............................................................................................. 5 4. 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

5. Plants compact (up to 0.6 m high), with thick succulent stems; flowering during the austral summer (November to February); confined to the Otjihipa Mountains in north-west Namibia............................................................................................... 6. T. kaokoensis

— Plants generally large (mature individuals generally more than 1.5 m high, often much more), with woody or slightly succulent stems; flowering during the winter months or during the dry season in the equatorial zone; widespread, but not known from the Otjihipa Mountains in north-west Namibia..................................................................... 6

6. 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........................... 7

7. Flowers pedicellate, pedicels ≥ 0.3 mm (male) or ± 0.3 mm (female) long; male inflorescence lax (internodes generally> 3 mm long); northern provinces of South Africa northwards to southern Tanzania.................................................................................................. 8

— Flowers subsessile or very shortly pedicellate, pedicels <0.3 mm long; male inflorescence dense, the axis often hardly visible (internodes generally <3 mm long); calices with pale yellow sessile glands or lacking sessile glands); Tanzania and adjacent parts of northern Malawi and north-east Zambia, north to Ethiopia and Sudan.................................... 9

8. 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

9. Stems with conspicuously raised leaf-abscission scars; leaves coarsely and deeply serrate, the primary teeth usually with conspicuous smaller marginal teeth; corolla tube very short: c. 0.8 (male) or 0.5 mm (female), lobes spreading; Burundi, Rwanda, Kenya, northern Tanzania, Uganda and adjacent parts of the Democratic Republic of the Congo, Ethiopia and Sudan........................................................................................... 10. T. urticifolia

— Stems with only slightly raised leaf-abscission scars; leaves crenate-dentate, the primary teeth usually lacking (or sometimes with very small) marginal teeth; corolla tube ± 1.2 (male) or 1.4 mm (female) long; south-west Tanzania, and adjacent parts of Zambia and Malawi............................................................................................... 9. T. tanganyikae