Leonardoxa africana (Baill.) Aubrév., 1993

Mckey, Doyle B., 2000, Leonardoxa africana (Leguminosae: Caesalpinioideae): a complex of mostly allopatric subspecies, Adansonia (3) 22 (1), pp. 71-109 : 95

Leonardoxa africana (Baill.) Aubrév.

Adansonia, ser. 2, 8: 179 (1968). — Humboldtia africana Baill., Hist. Pl. 2: 99 (1870).

— Type: Mann 726, Cameroon, Littoral Province, Cameroon River (= wouri estuary), 1861 (holo-, K; iso-, P) .

The description of Leonardoxa by LÉONARD (1993) is still generally accurate, but must be amended in the following ways to take into account the variation described here: twigs with or without a fusiform, hollow infra-nodal swelling; inflorescences axillary on young twigs, ramiflorous, or cauliflorous.

Key to the subspecies of Leonardoxa africana

Some of the characters included in the key follow predictable ontogenetic patterns. In small saplings and in sucker shoots from cuttings, for example, leaflets are smaller, fewer leaflet pairs are present, and fewer nectaries occur on each leaflet than in mature trees. The descriptions here, unless otherwise stated, apply to mature trees.

1. Internodes of young twigs not swollen or hollow, not inhabited by ants; leaflet apex short-acuminate; inflorescences axillary on small twigs up to about 5(-rarely 10) mm diameter; hypanthium white to pale lilac, corolla lilac ................................................................................................................ 4. subsp. gracilicaulis

1’. Internodes of young twigs (at least on all plants ≥ 1.5 m tall) swollen, with thickened pith, hollowed out and inhabited by ants; leaflet apex long-acuminate; inflorescences usually ramiflorous (on twigs> 10 mm diameter) or cauliflorous on large branches and trunk, rarely axillary on young twigs; hypanthium and corolla mauve to pink, purple or red ...................................................................................................................... 2

2. Young growth produced in flushes of a single internode at each branch tip, pith chamber thus restricted to single-internode segments; specialised swollen internodes present at all stages of growth, from seedling (20 cm tall) to adult; largest leaflets usually 13-15 cm long, 4.5-5.5 cm broad; (2-)3(-5) nectaries at base of each proximal leaflet ........................................................................................................................ 1. subsp. africana

2’. Young growth produced in flushes of 2-4 internodes at each branch tip, pith chamber thus continuous over 2-4 internodes; swollen internodes present only on plants ≥ 60 cm tall, seedlings lacking myrmecodomatia; largest leaflets usually 16-23 cm long, 6-8 cm broad; nectaries at base of each proximal leaflet variable in number, sometimes absent.................................................................................................................................. 3

3. Leaves often 4(3-5)-jugate; nectaries often absent at base of each proximal leaflet, when present usually 1(-2) in number; lowland rain forest up to 300 m elevation ...................................................... 2. subsp. letouzeyi

3’. Leaves usually 2(2-3)-jugate; nectaries at base of each proximal leaflet present on almost all plants, usually 2 in number; submontane rain forest in the Rumpi Hills (above 800 m), and possibly other hills in southwestern Cameroon.................................................................................................................... 3. subsp. rumpiensis Figures 3 and 4 show the distribution of field sites and herbarium collections, respectively, of each of the four infraspecific taxa recognised here.

Figures

Fig. 3. — Geographic distribution of field localities of members of the Leonardoxa africana complex: L. africana subsp. gracilicaulis = Group 1; L. africana subsp. rumpiensis = Group 2; L. africana subsp. letouzeyi = Group 3; L. africana subsp. africana = Group 4.

Fig. 4. — Geographic distribution of herbarium collections of the Leonardoxa africana complex examined in this study: L. africana subsp. gracilicaulis = Group 1; L. africana subsp. rumpiensis = Group 2; L. africana subsp. letouzeyi = Group 3; L. africana subsp. africana = Group 4.