Mischogyne Exell (1932)

Gosline, George, Marshall, Andrew R. & Larridon, Isabel, 2019, Revision and new species of the African genus Mischogyne (Annonaceae), Kew Bulletin 74 (28), pp. 1-23 : 7-8

Mischogyne Exell (1932) ;

R. E. Fries (1959); Paiva (1966); Le Thomas (1969). Type species: Mischogyne michelioides Exell

Trees or shrubs. Trunk straight, sometimes fluted, cylindrical, or shrubs branching from the base ( M. michelioides ). Very young leaf buds, leaves, and twigs with a soft brown indumentum of appressed hairs, quickly glabrous or glabrescent. Taeigs striate, light grey to dark grey to brown. Petioles terete, deeply grooved adaxially, glabrous to densely pubescent. Leaoes simple, entire, alternate, petiolate and exstipulate, lamina narrowly elliptic to obovate, chartaceous to coriaceous, often slightly bullate, glabrous to pubescent; dark glossy green above, lighter green below, drying olive green concolorous or paler below; midrib impressed on the upper side, raised on the lower side, glabrescent; secondary venation brochidodromous, prominent above and below; tertiary venation markedly reticulate on both surfaces of the lamina with reticulation net cells 0.6 – 1.8 mm wide. Inflorescence extra-axillary or terminal ( M. michelioides ) on young branches, single flowered (occasionally two flowers in M. gabonensis ). Bracts generally reduced to a tuft of hairs or early caducous. Floaeers bisexual. Sepals 3, reduplicate-valvate, free, enclosing the receptacle until anthesis ( Fig. 2A – C ), or united in a thin mem br a nou s c ap su le ru pt ur i ng at a nt h esi s ( M. gabonensis , Fig. 2D ). Petals 6, in two alternating whorls of three each, white, free, subequal, elliptic to ovate, pubescent, reflexing at anthesis except M. michelioides where the petals spread from the base. Receptacle extended as a torus, conical, cylindrical, or elongate in a thin flexible column, with stamens attached to the lower portion and carpels attached at the apex. Stamens numerous, spirally arranged, linear, latrorse, basifixed, appressed at least in lower part against the torus; filament minimal or absent; connective and thecae nearly the length of the anther; connective pubescent or glabrous, without expanded terminal extension, connective apex glabrous or terminated by a tuft of hairs. Sepals, petals and stamens dropping at end of anthesis, leaving the receptacle and carpels exposed. Carpels 3 – 12 (to 40 in M. michelioides ), cylindrical to ovoid, densely pubescent; style short or absent, stigma bilobed, ovules numerous, lateral, biseriate, placentation parietal. Fruits monocarps 1 – 3, ellipsoid, oblong to globose, pubescent to glabrous, smooth or with slight longitudinal ribs, constricted or not around the seeds, shortly stipitate, apiculate. Seeds 3 – 12 per monocarp, flattened to transversely ellipsoid, raphe raised to flat, ruminate with 15 – 20 membranous semicircular invaginations.

P O L L E N. P o l l e n i n t e t r a d s. E x i n e r e d u c e d, inaperturate, globose, tectum reticulate-perforate. ( Doyle & Le Thomas 2012) Only Mischogyne elliotiana ( Walker 1972) and Mischogyne congolana (Le Thomas 1980) have been examined. Doyle & Le Thomas (2012) give an overview of pollen in the Annonaceae , and show that Mischogyne pollen characters are largely congruent with other genera of Monodoreae . Le Thomas (1980) uses Mischogyne gabonensis as an example of “mixed structure of the infratectile layer”, differing slightly from other genera in the clade which have a “columellar structure”. Couvreur et al. (2008c) provide a survey of pollen in the other genera of the clade.

ECOLOGY. Evergreen or semideciduous equatorial or gallery forest, with 1000 – 4000 mm precipitation per annum (ppa); except Mischogyne michelioides : rivers, sandy areas, or among rocks at altitude 600 – 1000 m and 650 – 1000 mm rainfall ppa.

POLLINATION. No studies have been done. Saunders (2012) observed that the lack of a pollination chamber is “typical of small-beetle pollination”.

DISPERSAL. No scientific observations are known. Dispersal of Mischogyne congensis by snakes cannot be ruled out. “ Les indigènes prétendent que les serpents mangeant beaucoup le fruit de cet arbuste.” (Gilbert, G.C. 2321bis).

USES. Mischogyne congensis is used against snake bites (Gilbert 2321bis); M. michelioides for treatment of swollen legs (Damann 2557) and against madness (Santos 252). Mischogyne elliotiana var. sericea is used to clean hats and other cloth (Deighton 510).

ETYMOLOGY. μίσχος = stalk (Greek) + gyne for the elongate gynoecium of Mischogyne michelioides , the type species.

Key to the species of Mischogyne

1a Torus> 10 mm long, elongate flexible, leaves deciduous ( Angola)................. 5. M. michelioides

1b Torus <7 mm long, cylindrical or connate, leaves evergreen.................................. 2

2a Calyx with sepals united, opening by rupturing ( Fig. 2D ); (Coastal forests Cameroon, Bioko, Gabon)... 3. M. gabonensis

2b Calyx of 3 free reduplicate sepals, opening by separation at valvate sepal margins ( Fig. 2A, B, C )....... 3

3a Tree to 20m tall, leaves 16 – 32 cm long (Usambara Mountains, Tanzania)................ 4. M. iddii

3b Shrub or small tree 3 – 10 m tall, leaves 8 – 20 cm long (West and Central Africa)................. 4

4a Leaves with a wax gloss above and below, secondary nerves ascending at 10° – 30° angle to midrib, to 10 – 20% of the leaf length before anastomosing; stigma sessile; older petioles glabrous (mid-Congo riverine)............................................................ 1. M. congensis

4b Leaves matte below, secondary nerves ascending at 30° – 45° angle to midrib, to 25 – 30% of the leaf length before anastomosing; stigma on short style; all petioles with indumentum (West Africa).............. 5

5a Young leaves glabrous; secondary nerves 6 – 9; acumen 8 – 15% of the leaf length... 2a. M. elliotiana var. elliotiana .

5b Underside of young leaves with straight white hairs 0.8 – 1.2 mm long, secondary nerves 9 – 12; acumen 20 – 25% of the leaf length.......................................... 2b. M. elliotiana var. sericea

Figures

Fig. 2. Flower buds of Mischogyne species. A M. elliotiana var. elliotiana with old flower showing carpels below (Dalziel 761 [K000874259]); B M. michelioides showing large terminal bud (Gossweiler 9379 [K000196792]); C M. congensis (Evrard 5376 [BR0000015312655]); D M. gabonensis buds showing capsule and rupturing at anthesis (Le Testu 1768 [WAG0247284]).