Isolona Engl., Nat. Pflanzenfam. Nachtr. I: 161 1897
Creators: name: Couvreur, Thomas L. P.
name: Dagallier, Leo-Paul M. J.
name: Crozier, Francoise
name: Ghogue, Jean-Paul
name: Hoekstra, Paul H.
name: Kamdem, Narcisse G.
name: Johnson, David M.
name: Murray, Nancy A.
name: Sonke, Bonaventure
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Magnoliales
Annonaceae
Isolona

description: Isolona Engl., Nat. Pflanzenfam. Nachtr. I: 161, 1897 Type species. <i>Isolona madagascariensis</i> (A.DC.) Engl. &amp; Diels (a species from Madagascar). Description. Trees, 3-30 m tall, d.b.h. 5-60 cm; stilt roots or buttresses absent. Indumentum of simple hairs or glabrous. Leaves: petiole 1-15 mm long, 1-4 mm in diameter, blade 8.5-29 cm long, 3-15 cm wide, elliptic or obovate or oblong, apex acuminate, base decurrent to rounded or acute, concolorous; midrib <b>raised on upper surface</b>; secondary veins 7 to 20 pairs; tertiary venation reticulate. Inflorescences ramiflorous on old leafless or young foliate branches, axillary. Flowers bisexual with 9 perianth parts in 2 whorls, 1 to 3 per inflorescence; pedicel 1-25 mm long, 1-2 mm in diameter; in fruit 2-29 mm long, 2-5 mm in diameter; bracts 2 to 7, several basal and one upper, lower half of pedicel; sepals 3, valvate, free, 1-9 mm long, 2-5 mm wide, ovate or elliptic, apex acute or acuminate or rounded, base truncate; <b>petals 6, basally fused</b>, tube 3-11 mm long, <b>inner and outer whorl not differentiated</b>, equal; lobes 6-31 mm long, 2-12 mm wide; stamens numerous, in 3 to 4 rows, 1-2 mm long, broad; connective discoid; staminodes absent; <b>carpels fused - syncarpous, forming a single visible gynoecium</b>, 1-3 mm long, stigma bilobed, slightly capitate or capitate. <b>Fruit syncarpous</b>, <b>forming a single visible fruit</b>, 30-90 mm long, 15-50 mm in diameter, ovoid or ellipsoid, apex apiculate or rounded or cuspidate; seeds numerous not seriate, 8-25 mm long, 5-15 mm in diameter, ellipsoid or flattened ellipsoid; aril absent. A genus of trees with 20 known species, 15 in Africa and 5 in Madagascar. In Cameroon nine species are known, none endemic. <i>Isolona</i>, together with its sister genus <i>Monodora</i>, are unique in Annonaceae in having truly syncarpous flowers (fused carpels) and fruits. This translates into single fruits with unordered seeds, in contrast to other genera which have either uni- or biseriate placentation. Petals in <i>Isolona</i> are basally fused forming a clearly visible tube, with six equal lobes of equal length in a single whorl. In the vegetative state, <i>Isolona</i> and <i>Monodora</i> (together with <i>Polyceratocarpus pellegrinii</i>) are characterized by a raised midrib, in contrast to a sunken or flat midrib in all other genera found in Cameroon. Taxonomy. Couvreur (2009).
description: Published as part of <i>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. &amp; Sonke, Bonaventure, 2022, Flora of Cameroon - Annonaceae Vol 45, pp. 1-532 in PhytoKeys 207</i> on pages 129-130, DOI: 10.3897/phytokeys.207.61432
description: {"references": ["Couvreur, TLP, 2009. Monograph of the syncarpous African genera Isolona and Monodora (Annonaceae). Systematic Botany Monographs 87: 1 - 150"]}