1 | Stamens inserted very clearly around the middle or in lower half of corolla tube, ≤ 0.6 of corolla tube length |
1' | Stamens inserted in upper half of corolla tube, > 0.6 of corolla tube length |
2 | Sepals acute, rarely obtuse but never rounded |
2' | Sepals rounded |
3 | Inflorescence robust, glabrous to densely pubescent; branchlets glabrous to densely pubescent, terete to very weakly angled. — Peninsular Malaysia |
3' | Inflorescence delicate, glabrous; branchlets glabrous, weakly angled to strongly winged. — Borneo |
4 | Corolla tube ≤ 20 mm long |
4' | Corolla tube > 20 mm long |
5 | Branchlets sparsely to densely puberulent, glabrescent when older; petiole sparsely to densely pubescent; sepals densely puberulent |
5' | Branchlets glabrous; petiole glabrous; sepals glabrous to sparsely puberulent |
6 | Secondary veins 24-32 pairs; corolla lobes < 7 times as long as wide |
6' | Secondary veins 16-19 pairs; corolla lobes > 8 times as long as wide |
7 | Inflorescence lax with clear internodes, sparsely to densely puberulent; pedicels 2.1-5 mm long |
7' | Inflorescence with flowers clustered along short or elongated branches, glabrous or puberulent only in upper parts; pedicels 1-2 mm long |
8 | Petiole 4-7 mm long; pedicels 2.1-3.5 mm long; corolla throat pubescent, corolla lobes 9.5-12.3 mm long; disk pubescent; ovary densely pubescent |
8' | Petiole 1-2 mm long; pedicels 4.5-5 mm long; corolla throat glabrous, corolla lobes 11.5-15 mm long; disk glabrous; ovary glabrous |
9 | Leaf apex caudate, secondary veins clearly discernable from tertiary venation, curved ascending; corolla white, lobes 1-1.5 mm wide |
9' | Leaf apex short acuminate, secondary veins not clearly discernable from tertiary venation, straight; corolla red, lobes 2.2-2.3 mm wide |
10 | Leaves sessile |
10' | Leaves petiolate |
11 | Corolla white and tinged pink or pink with a red eye; anther apex < 2 mm from corolla throat |
11' | Corolla completely white or white with a yellow eye, rarely pinkish white; anther apex > 2 mm from corolla throat |
12 | Disk pubescent; inflorescence lax with distinct internodes |
12' | Disk glabrous; inflorescence variable |
13 | Petioles delicate, 6-17 mm long, usually around 15% of total leaf length; inflorescence axes < 1 mm wide |
13' | Petioles robust, 3-12.5 mm long, less than 15% of total leaf length; inflorescence axes > 1 mm wide or rarely less but then corollas not white with a red eye |
14 | Anther apex 5.2-5.8 mm from corolla throat; inflorescence > 10 cm long, densely puberulent |
14' | Anther apex 0.1-5 mm from corolla throat; inflorescence length variable but mostly < 10 cm long, puberulent or not |
15 | Inflorescence with bracts as large as the sepals and flowers clustered at inflorescence branch ends; sepals mostly acute, more rarely obtuse; fruit without a spur or angle |
15' | Inflorescence with bracts somewhat obscure or smaller than sepals, if as large as sepals then flowers not clustered at inflorescence branch ends; sepals obtuse to rounded; fruit with a spur or angle on one side |
16 | Ovaries glabrous or with just a few isolated hairs |
16' | Ovaries clearly pubescent |
17 | Leaves with long caudate apex; secondary veins at 40-60° from midrib. — Borneo |
17' | Leaves acuminate; secondary veins at (45-)60-75° from midrib. — Not in Borneo |
18 | Stamen bulge slightly below top of corolla tube; flowers white or pinkish but not white with a strongly contrasted pink or red ‘eye’. — Southern Thailand, Peninsular Malaysia |
18' | Stamen bulge at top of corolla tube; flowers white with a strongly contrasted pink or red ‘eye’. — Philippines, Eastern Malesia, Western Pacific Islands |
19 | Inflorescence robust and lax with distinct internodes all through inflorescence |
19' | Inflorescence robust or delicate with flowers congested, if lax then at least with ultimate branches congested |
20 | Inflorescence without elongated branches; corolla pale to dark pink or white with a red or pink ‘eye’ |
20' | Inflorescence with elongated branches but with the flowers congested along these; corolla white or white with a yellow ‘eye’, very rarely with a pink tinge but then only ever one flower on an inflorescence branch open at a time |
21 | Branchlets pubescent; native in Burma but widely cultivated |
21' | Branchlets glabrous; wild |
22 | Peduncle to 1 cm long; fruit with a large deltoid or very slightly hooked projection on one side. — Philippines, Eastern Malesia, Western Pacific Islands |
22' | Peduncle mostly > 1 cm long, very rarely under 1 cm; fruit with only a slight angle on one side. — Peninsular Malaysia |
23 | Secondary veins at (55-)60-80° from midrib; anther apex 2.4-5 mm from corolla throat |
23' | Secondary veins at 40-60° from midrib; anther apex 1.1-2 mm from corolla throat |