Stylochaeton, Leprieur, 1834

Struwig, Madeleen, Le Roux, Precious T., Siebert, Stefan J. & Van Wyk, Abraham E., 2023, Two new species of Stylochaeton (Araceae: Aroideae) from South Africa, Phytotaxa 620 (1), pp. 1-17 : 3-4

Key to the species of Stylochaeton in southern Africa ( Eswatini, Mozambique, South Africa and Zimbabwe)

1. Leaves with blade subcircular, adpressed to the soil surface ....................................................................................... S. europhyllum

- Leaves with blade sagittate to cordate, erect, not adpressed to the soil .............................................................................................2

2. Leaves with blade oblong to triangular (broadly cordate, cordate-sagittate, subcordate), up to 300 mm wide.................................3

- Leaves with blade sagittate or hastate, up to 180 mm wide ...............................................................................................................5

3. Petiole up to 180 mm long; blade up to 160 mm long, apex ending in a cusp (0.7 mm long); spathe swollen at the base, followed by a constriction, swollen again above the constriction; male and female flowers separated by a naked axis ca. 19 mm long.......... ....................................................................................................................................................................................... S. tortispathus

- Petiole up to 430 mm long; blade up to 330 mm long, apex rounded, acute, acuminate or apiculate; spathe slightly inflated at the base only; male and female flowers separated by a naked axis ca. 1 mm long..................................................................................4

4. Leaf blade with basal lobes usually separated by a broad sinus; adaxial surface glabrous; inflorescence appearing with or after the leaves; spathe borne entirely above-ground, greenish to yellowish or purplish, limb straight when dry, female part cylindrical; infructescence borne above-ground.................................................................................................................................. S. natalense

- Leaf blade with basal lobes separated by a narrow sinus; adaxial surface pubescent, especially dense on the veins; inflorescence appearing before the leaves; spathe with base ca. subterranean, cream-coloured, limb twisted when dry; female part hemispherical; infructescence borne partly below-ground level .............................................................................................................. S. puberulus

5. Leaf blade with basal lobes shorter (ca. 25–64 mm) than apical lobe (ca. 64–152 mm) (sometimes as long as apical lobe); spadix with male and female flowers separated by a 2–12 mm zone of few to 10 sterile flowers; filaments somewhat to greatly thickened towards apex................................................................................................................................................................... S. borumense

- Leaf blade with basal lobes (ca. 20–160 mm) and apical lobe (ca. 24–172 mm) of almost equal length; spadix with male and female flowers contiguous; filaments not thickened......................................................................................................................................6

6. Leaf blade with basal and apical lobes linear, leathery, greenish blue; petiole glabrous; petiolar sheath narrowing gradually to apex but not ligulate; spadix projecting out from the spathe tube .................................................................................... S. glaucophyllum

- Leaf blade with basal and apical lobes elliptic, green; petiole with distal ¼ above sheath often with scattered trichomes; petiolar sheath ligulate, extending distally into two slender, curling elongations (ligulae) up to 30 mm long; spadix enclosed in the spathe tube .......................................................................................................................................................................... S. sekhukhuniense