Introduction
In January 2006, the author joined Gilfrid Powys on a road trip from Kenya to north east Uganda to visit Kidepo National Park. To shorten the journey it was decided to cross to Uganda via the seldom used Kenyan border post of Oropoi. This border post is in Turkana District, in the north west of Kenya, at the base of the Rift Valley directly facing the Ugandan escarpment and south of Kidepo National Park. In our haste to reach Kidepo, no time was spent on the escarpment. However, on the way back it was decided to explore the top of the steep Ugandan escarpment overlooking the Kenyan plain. The area, because of its high altitude, receives considerably more rainfall then the arid lowland of north-west Kenya, and has lush Juniper forest on the mountain tops, interspersed, on the lower slopes, with large grassland areas dominated by tall Hyparrhenia spp. and scattered plants of woody genera, such as Acacia, Erythrina and Combretum spp. The area is the home of the Ik, hunter gatherers and today subsistence farmers, numbering a few thousand, and the subject of a controversial anthropological study a few years back (Turnbull 1972). Succulents were our main quest though obviously the dense tall grass made such search a hopeless case (Fig. 1). After several hours of fruitless searching we were ready to call it a day when, while following a tortuous path to a farm house, a familiar shape was noted! It was a smallish, single stemmed aloe growing almost on the path. A rapid search amongst the surrounding grasses revealed several others. The plant most closely resembled Aloe lateritia var. graminicola (Carter 1994, Carter et al. 2011) and more distantly another species, Aloe wollastonii, which was previously named Aloe lateritia var. kitaliensis (Reynolds 1966), but the presence of clear morphological differences suggested that the plant could be a new taxon (Table 1).
1
Ugandan escarpment overlooking the Kenyan border. Several plants of Aloe ikiorum are scattered among tall Hyparrhenia spp. grass. Find them!
Table 1:
Comparison of Aloe ikiorum and its presumed closest relatives
Diagnosis and description
Aloe ikiorum Dioli & G. Powys sp. nov., A. lateritiae var. graminicolae (Reynolds) S. Carter affinis, sed foliis angustoribusis et tenuioribus, inflorescentiis et bracteis floralibus longioribus, perianthiis et pedicellis brevioribus distinguitur.
Type locality: Uganda, Karamoja Region, Kaabong District, among tall Hyparrhenia spp. on the escarpment overlooking Kenyan border, 3° 39′ N, 34° 17′ E, c 1.900 m, 5th January 2006, Dioli 116 (holotypus ABH58276! photo FT! photo EA!).
Plant: solitary, medium sized, growing among dense Hyparrhenia spp. (Fig. 2a–c).
Stem single, rarely branched, recumbent then erect, 20–30 × 5–7 cm, with some dried leaf remains persistent thereon. In cultivation, the stem apex branches profusely (Fig. 3).
Leaves 12–24, in a dense rosette, spreading, lanceolate, 20–40 × 4–6 cm, thin, ca. 0.3–0.5 cm thick at the base, and easily broken, smooth, upper surface bright green and lower surface paler grey-green. In dry conditions, upper surface reddish-brown to grayish-green, lower surface paler grey-green, with apex of older leaves dry and curled (Fig. 2b). Surfaces profusely, yet obscurely, striated longitudinally by thin white-greenish lines which are more distinct on the lower surface; juvenile plants abundantly spotted, adult plants generally unspotted, occasionally some adult plants with lenticular spots ca. 8 × 2 mm, scattered or in irregular transversal lines, more visible on the upper surface; margins whitish with soft uncinate brown tipped teeth ca. 2 mm long, 4–16 mm apart (or 8–10 teeth per 10 cm). Exudate pale yellow when fresh, to yellowish-brown, changing to chestnut-brown when dry.
Inflorescence erect 85–155 cm high, with 4 –5 branches, widely spreading. Peduncle greenish-grey, fleshy, basally flattened, ca. 15 mm wide at base, with bracts ca. 30 × 8 mm subtending the branches, and several narrow bracts ca. 2–20 mm below the main raceme (Fig. 4). Racemes erect, densely capitate 3–8 cm long (Fig. 5). Floral bracts reflexed to subtending ca. 18 × 2 mm, papery linear-lanceolate with 1–3 dark brown lines. Pedicels ca. 10–13 mm long. Perianth pinkish-red, fading to pale yellow in the upper third, curved, glabrous, cylindric and slightly trigonous with basal swelling, ca. 24 mm long, 6 mm across at the ovary, slightly constricted above to 4 mm then widening toward the mouth, outer tepals free for 8–10 mm with slightly spreading tips. Buds with greenish tips (Fig. 6). Stamens and Style scarcely exserted. Capsule ovoid, ca. 30 mm long
Etymology: This species is named after the Ik, the ethnic group living in the area where the plant was discovered.
Acknowledgements
The author wishes to thank Gilfrid Powys for his suggestions and generous support, Susan Carter for again assisting with text and Latin translation, and two anonymous reviewers for useful suggestions.
