KEY TO GENERA IN MADAGASCAR [pdf]

by William R. Anderson
1. Calyx bearing 1 large elliptical decurrent abaxial gland; petals fimbriate; exotic vine escaped from cultivation.
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Hiptage benghalensis (L.) Kurz: photos, drawing
1. Calyx eglandular or bearing up to 5 small circular abaxial glands; petals entire, denticulate, or coarsely dentate; native species.
2. Leaves up to 5 mm wide; petals narrowly spatulate and densely sericeous over whole abaxial surface; styles distally bifurcated; flowers unisexual, plants dioecious.
Digoniopterys microphylla Arènes: drawing
2. Leaves at least 1 cm wide, mostly much wider; petals elliptical to orbicular, glabrous or thinly sericeous on abaxial keel; styles entire; flowers bisexual or unisexual, if unisexual the plants dioecious.
3. Specimens bearing flowers.
4. Corolla bilaterally symmetrical, bearing 2 upper lateral petals, 2 lower lateral petals, and 1 lower petal on the plane of symmetry, the petals at least subtly dissimilar; petals yellow; anthers poricidal (i.e., dehiscing by means of oblique subapical pores or short slits); flowers all bisexual.
5. Pedicels sessile; limb of petals coarsely dentate; styles usually 2, sometimes with a third style developed; leaves mostly alternate, but opposite or subopposite in some species.
Acridocarpus - sample taxon - A. adenophorus Adr. Juss.: drawing
5. Pedicels pedunculate; limb of petals entire or denticulate; style usually 1, sometimes with a second, usually shorter, style developed; leaves mostly opposite, sometimes subopposite or in verticils of 3 or 4.
Tristellateia - sample taxa - photos: T. greveana, T. madagascariensis -
drawings: T. greveana, T. madagascariensis
6. Stipules enlarged, resembling miniature leaves, persistent; flowers all appearing bisexual but probably functionally dioecious, borne in elongated axillary pseudoracemes of 8 or more, with definite internodes between successive flowers.
Madagasikaria andersonii C. Davis - photos, drawing
6. Stipules tiny, triangular, persistent or deciduous; flowers bisexual or unisexual, borne in umbels or corymbs of 4–many, with internodes not or hardly present between successive flowers.
7. Flowers borne in umbels of 4; pedicels sessile.
Philgamia and Sphedamnocarpus (distinguishable only in fruit; see fruit key below).
7. Flowers borne in corymbs of 4–13 or many-flowered umbels; pedicels pedunculate, the peduncle sometimes very short.
8. Ovary bearing initials for lateral wings and dorsal crest on each carpel, visible even in young flowers (see also fruit key below).
Microsteira - sample taxa - photos: M. axillaris, M. ambovombensis, M. sp. - drawings: M. ambovombensis, M. diotostigma
8. Ovary lacking any obvious sign of initials for wings or crests (see also fruit key below).
Rhynchophora - photos: R. humbertii, R. phillipsonii -
drawings: R. humbertii, R. phillipsonii
3. Specimens bearing fruits.
9. Fruits indehiscent at maturity, bearing 3 or 4 horizontal wings radiating from the body of the fruit.
Rhynchophora - photos: R. humbertii, R. phillipsonii -
drawings: R. humbertii, R. phillipsonii
9. Fruits dehiscent at maturity, breaking apart into 2 or 3 variously winged mericarps, the wings rudimentary in Philgamia.
10. Mericarp with the wing reduced to a rudimentary dorsal crest, negligible relative to the size of the nut.
Philgamia - sample taxa - photos: P. glabrifolia -
drawings: P. glabrifolia, P. hibbertioides
10. Mericarp with wing(s) well developed, the wings dorsal or lateral or both.
11. Mericarp a samara with a single elongated dorsal wing, the sides of the nut unwinged.
12. Flowers borne in elongated, many-flowered pseudoracemes.
Acridocarpus - sample taxon - A. adenophorus Adr. Juss.: drawing
12. Flowers borne in umbels of 4.
Sphedamnocarpus - sample taxa - drawings: S. dubardii, S. poissonii, S. sp.
11. Mericarp a samara with a single elongated dorsal wing, the sides of the nut unwinged.
13. Samara with the lateral wing elliptical, entire.
Madagasikaria andersonii C. Davis - photos, drawing
13. Samara with the lateral wing dissected, divided to the nut at the apex or variously divided into lateral subdivisions.
14. Samara with the single lateral wing divided to the nut at the apex and therefore Y-shaped with 2 elongated upper lobes and a shorter basal lobe, the lateral wing membranous; flowers borne in many-flowered umbels.
Microsteira - sample taxa - photos: M. axillaris, M. ambovombensis, M. sp. - drawings: M. ambovombensis, M. diotostigma
14. Samara with the lateral wings divided into 4–10 elongated winglets proximally thickened with spongy aerenchyma; flowers borne in elongated pseudoracemes.
Tristellateia - sample taxa - photos: T. greveana, T. madagascariensis -
drawings: T. greveana, T. madagascariensis
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4. Corolla radially symmetrical, the petals all alike; petals white or yellow; anthers dehiscing longitudinally; flowers bisexual or unisexual, if unisexual the plants dioecious.