Alangium

de Wilde, W. J. J. O. & Duyfjes, B. E. E., 2017, The species of Alangium section Rhytidandra (Alangiaceae), Blumea 62 (1), pp. 75-83 : 76

ALANGIUM SECTION RHYTIDANDRA

The key presented here is largely based on flowering specimens.Although construction of a dichotomous key is impractical for fruiting specimens, most can nevertheless be identified with the help of fruit size and provenance, as follows:

Fruit length (mm) species

8–12 pilosum ( Philippines, Lesser Sunda Is.)

10–15 villosum (Java)

12–15 strigosum ( Papua New Guinea: Madang, Sepik)

13–15 brassii ( Papua New Guinea: Milne Bay) 15 polyosmoides (E Australia),

velutinum ( Papua New Guinea)

15‒20 gracile ( Papua New Guinea)

15– 22 warburgianum ( Moluccas: Bacan)

17– 22 solomonense (Solomon Is., Bougainville), vitiense ( Fiji, Vanuatu, New Caledonia)

(25‒)30 glabrum ( Papua New Guinea)

30–35 ferrugineum ( Moluccas, New Guinea)

unknown guadalcanalense (Solomon Is.)

1. Flowers larger; corolla in bud 9 mm long or more..... 2

1. Flowers smaller; corolla in bud 8 mm long or less... 10

2. Calyx lobes long-triangular, c. 1.5 mm long. ― Bacan Isl..............................13. A. warburgianum

2. Calyx lobes ± triangular, c. 0.5 mm long or lobes almost absent...................................... 3

3. Ovary and calyx in bud reddish brown-hairy. Leaves drying reddish brown. ― New Guinea................... 4

3. Ovary and calyx in bud greyish brown or yellowish brown-hairy. Leaves drying greenish. ― New Guinea, Australia, Solomon Isl................................... 6

4. Corolla in bud slender, c. 1 mm diam. Peduncle c. 0.5 mm diam. Style glabrous. Fruit 15–20 mm long 4. A. gracile

4. Corolla in bud thickish, c. 1.5 mm diam. Peduncle 1‒2 mm diam. Style (sparingly) hairy or glabrous. Fruit 15–35 mm long........................................ 5

5. Lower lamina surface densely hairy but not velutinous. Style (sparingly) hairy. Fruit longly narrowed towards apex, 30‒35 mm long. ― Lowland forest... 2. A. ferrugineum

5. Lower lamina surface velutinous. Style glabrous. Fruit not longly narrowed towards apex, c. 15 mm long. ― Montane forest, 1400–2600 m altitude........ 10. A. velutinum

6. New Guinea. Style glabrous..................... 7

6. Australia or Solomon Isl. Style hairy............... 9

7. Calyx lobes shorter than limb, in fruit hardly visible (rim of calyx almost straight), and not connivent... 1. A. brassii

7. Calyx lobes about as long as or longer than limb, in fruit connivent.................................... 8

8. Twig towards apex brown-hairy, hairs 0.5(–1) mm long. Fruit c. 15 mm long................. 9. A. strigosum

8. Twig glabrescent (hairs less than 0.5 mm long). Fruit (25–) 30 mm long.................... 3. A. glabrum

9. Filaments completely fused with the tube of the corolla. ― Solomon Isl. (Guadalcanal Isl.).. 5. A. guadalcanalense

9. Filaments largely free. ― East Australia.................................. 7. A. polyosmoides (2 subsp.)

10. Corolla in bud 4–6(–7) mm long. ― Philippines, Lesser Sunda Isl. ( Moluccas)................. 6. A. pilosum

10. Corolla in bud (6–) 7–8 mm long................. 11

11. Twig towards apex, leaves, inflorescences and flowers densely hairy. ― Java ................11. A. villosum

11. Twig towards apex, leaves, inflorescences and flowers (sub)glabrous. ― Pacific area................... 12

12. Style glabrous or sparingly hairy. ― Fiji, Vanuatu, New Caledonia......................... 12. A. vitiense

12. Style hairy. ― Solomon Isl......... 8. A. solomonense