Croton, LEANDRI, 1939

Kainulainen, Kent, Ee, Benjamin van, Razafindraibe, Hanta & Berry, Paul E., 2017, A revision of the Adenophorus Group and other glandular-leaved species of Croton (Euphorbiaceae) from northern Madagascar and Mayotte, including three new species, Candollea 72 (2), pp. 371-402 : 374

Key to the species of Croton from northern Madagascar and Mayotte with glands on the underside of the leaf blades

1. Flower buds maturing evenly along the inflorescence, not tightly packed into a catkin-like structure, with anthesis occurring either ± simultaneously or sporadically along the length of the inflorescence ............................................. 2

1a. Flower buds maturing acropetally, with anthesis occurring sequentially from the base of the inflorescence, the distal end very compact and catkin-like .................................. 3

2. Floral buds evenly distributed along the inflorescence axis, inflorescence 0.2-1(-2) cm long; staminate and pistillate pedicels 2-5 mm long in bud; plants with stellate trichomes only................................................. C. nudatus

2a. Floral buds clustered in interspersed cymules along the inflorescence axis, inflorescence 3-10(-18) cm long; staminate pedicels 0.5-1 mm long in bud, pistillate pedicels 1-3.5 mm long in bud; plants with lepidote trichomes or a mixture of stellate and lepidote ones ........... C. stanneus

3. Ovaries and capsules hirsute or bristly (trichomes with long-protruding porrect rays)......................................... 4

3a. Ovaries and capsules with stellate trichomes (rays of the trichomes not porrect or long-protruding)...................... 6

4. Stipules fimbriate; mature capsules ≥ 10 mm diam., the endocarp c. 2 mm thick............................. C. loucoubensis

4a. Stipules entire or shallowly incised; mature capsules <7.5 mm diam., the endocarp <1 mm thick ................................. 5

5. Leaves markedly shaggy-hirsute with long-porrect trichomes; bracts not extending beyond the buds ............. ................................................................. C. tsiampiensis

5a. Leaves with woolly pubescence trichomes on the abaxial side; bracts extending well beyond the buds ..................... ................................................................ C. sahafariensis

6. Sepals of pistillate flowers usually green-foliaceous, unequal in size; stipules usually foliaceous, narrowly ovate, often with an auriculate base ............................. C. adenophorus

6a. Sepals of pistillate flowers not green or foliaceous, all of equal size; stipules narrowly lanceolate to acicular, the base not auriculate ................................................................. 7

7. Young branches glossy dark reddish-brown; mature leaves ± entire, glabrous (softly pubescent when young), the base rounded to truncate or shallowly cordate ..... C. scoriarum

7a. Young branches dull pale gray or tan; mature leaves denticulate to dentate, with stellate trichomes, scabrous to scurfy on young leaves, the base cordate......................... 8

8. Petioles, inflorescences, and young shoots densely covered by reddish, granulate trichomes; pistillate flowers with well-developed petals ................................... C. bathianus

8a. Petioles, inflorescences, and young shoots covered by whitish stellate trichomes, or tan scurfy ones; pistillate flowers lacking petals or with reduced, filamentous petals ....................................................................................... 9

9. Stipules lanceolate, serrate-margined, aristate, 10-20 mm long; inflorescences 6-10 cm long.................. C. mayottae

9a. Stipules awn-shaped, entire-margined, 5-10 mm long; inflorescences 1-6.5 cm long .......................... C. orangeae