Piptostigma Oliv., J. Linn. Soc., Bot. 8: 158, 1864

Couvreur, Thomas L. P., Dagallier, Leo-Paul M. J., Crozier, Francoise, Ghogue, Jean-Paul, Hoekstra, Paul H., Kamdem, Narcisse G., Johnson, David M., Murray, Nancy A. & Sonke, Bonaventure, 2022, Flora of Cameroon - Annonaceae Vol 45, PhytoKeys 207, pp. 1-532 : 277-278

Piptostigma Oliv., J. Linn. Soc., Bot. 8: 158, 1864

= Phaeanthus Hook. f. & Thoms. sect. Piptostigma (Oliv.) Baillon Hist. Pl. 4: 287 1878.

Type species.

Piptostigma pilosum Oliv.

Description.

Trees, 1-20 m tall, d.b.h. up to 21 cm; stilt roots or buttresses absent. Indumentum of simple hairs. Leaves: petiole 2-11 mm long, 1-6 mm in diameter; blade 7-66 cm long, 3-3 cm wide, ovate or elliptic or obovate or oblong, apex acuminate to emarginate, acumen 0.2-2.7 cm long, base cordate to decurrent, blade inserted on top of the petiole, discolorous, whitish below; midrib sunken or flat; secondary veins 14 to 65 pairs; tertiary venation percurrent. Inflorescence variable in length from compact to lax, composed of a peduncle like base and axial internodes. Individuals bisexual; inflorescences cauliflorous or ramiflorous on old leafless branches, axillary, 1 to 28 per inflorescence; pedicel 2-20 mm long; in fruit 9-25 mm long; bracts 2, one basal and one upper towards the lower half of pedicel; sepals 3, valvate, free, 2-12 mm long, apex acute or acuminate, base truncate; petals free, valvate, outer petals shorter than inner; outer petals 3, 5-28 mm long, 1.5-11 mm wide, elliptic or ovate or obovate, apex acute or acuminate, base truncate; inner petals 3, valvate, 15-80 mm long, 4-20 mm wide, elliptic or ovate, apex acute, base truncate; stamens numerous, 1-2 mm long, broad; connective discoid; staminodes absent; carpels free, 1 to 15, ovary 1-3 mm long, stigma globose or lobed. Monocarps sessile, 1 to 6, 13-65 mm long, 8-40 mm in diameter, globose to oblong, apex acute or rounded or cuspidate; seeds biseriate, 1-15 mm long, 2-10 mm in diameter, ellipsoid; aril absent.

A genus of 13 species from West and Central Africa (no species yet known from East Africa); all species are present in Cameroon, six endemic, making it the center of diversity for this genus.

Piptostigma and Brieya are the only Annonaceae genera in Cameroon with longer inner petals than outer. Piptostigma has spectacular inflorescences that are unique among Cameroonian Annonaceae . They appear complex, but are in fact simple and, the different inflorescence types are an important character to identify species. First, inflorescences appear to be "stalked “stalked”, that is they have a short woody peduncle at the based on the inflorescence structure and is probably the result of fallen old inflorescences. This peduncle is variable in length. Then follows the indeterminate part or sympodial rachis, which contains axial internodes variable in length. Different lengths between the internodes will lead to different overall aspects of the inflorescence. Following Ghogue et al. (2017) and Maas et al. (2003) we can distinguish three types:

compact: internodes are shorter than 1 cm giving a very compact appearance to the inflorescence.

lax or sub-lax: internodes are between 1 and 4 cm long, leading to more or less long inflorescences. This is found in most species.

panicle-like: internodes between 5 and 10.5 cm long leading to long pendant inflorescences.

We shall refer to these terms in the descriptions below and the key. Finally, we end up with the pedicel and flower per se.

Taxonomy.

Ghogue et al. (2017).