Key to Dillenia species in Peninsular Malaysia

There are many diagnostic characters where one can use to distinguish Dillenia species in Peninsular Malaysia. Many taxonomists uses the characteristics of the reproductive (flower/fruit) parts to create their key. Therefore, it is dificult when such parts are unavailable due to the season during collections that were being carried out. In order to have a friendly user key, i had created a new key which combines both vegetative and reproductive characteristics as below. I hope this key will be useful for those who needs to key out Dillenia species in Peninsular Malaysia. I had presented this key in the Flora Malesiana Symposium (FM8) in Singapore Botanic Gardens on August 2010.

Key to Dillenia species in Peninsular Malaysia

1.Petiole amplexicaul, winged…………………………..........2
Petiole non-amplexicaul, not winged………………...........3
2.Tree; wing constricted at leaf base; flower white……………...D. albiflos
Shrub; wing not constricted at leaf base; flower yellow...D. suffruticosa
3.Petiole with gutter; half-rounded, glabrous to sparse to moderately hirsute…....4
Petiole without gutter; rounded, moderate to densely hirsute……………7
4.Margin entire and smooth; apex rounded to emarginate; secondary veins

glabrous on both surfaces……………………………….D. pulchella
Margin not entire and coarse; apex acute to obtuse; secondary veins

> 9 pairs; pubescent on both surfaces……………5
5. Inflorescence-raceme; stamens purple; fruit dehiscent…......D. excelsa
Solitary flower; stamens not purple; fruit indehiscent……………………….6
6.Petiole smooth; petal white; stamens yellow in 2 less conspicuous rings................D. indica
Petiole slightly winged (decurrent leaf); petal yellow; stamens yellow to

pale yellow in 2 conspicuous rings.....................................D. obovata
7.Leaf apex acuminate to acute; base cuneate to acute…….D. sumatrana
Leaf apex acute to obtuse; base acute to obtuse…………………….............8
8.Small buttress; leaf base asymmetric; solitary flower…………D. ovata
Stilt roots; leaf base not asymmetric; inflorescence-raceme………………9
9.Dry leaf (underside) red to purplish brown; tertiary veinlets

inconspicuous and not raised; without petal…….....D. grandifolia
Dry leaf (underside) golden brown; tertiary veinlets conspicuous and

raised; with petal…….....................................................D. reticulata

Happy botanizing Dillenia! I'm currently involved in another genus (Melastoma) also in the Subclass of Dilleniidae . So, it's Melastoma hunting for this year which is why i did't got the chance to update much on Dillenia.