The Aglaias, mahoganies and their relatives (trees of the Meliaceae family) are a good interesting group to try getting your head around once you have been looking at tropical plants for a while. In North Queensland, this group of trees include members from the genus Aglaia, Dysoxylum, Chisocheton, Melia, Synoum, Toona and a few others.
Do pardon any mistakes and also the lack of a number of species as I am myself at the moment trying to get acquainted with this fascinating group of trees and will be updating this page as I go along. And any “Meliologists” out there or anyone who spots anything amiss, please feel free to correct me!
Basically, this group of plants usually have alternately arranged compound leaves with a terminal leaflet, and no stipules (yes, the absence of a trait can be a good trait!). Often also, the leaf (not leaflet) stalk is swollen at the point of attachment to the stem.
First off, the White Cedar (Melia azedarach) should be the easiest to learn and recognize, so there is absolutely no excuse not to know it.
The leaves are two times pinnate, and the leaflets are very distinctively toothed. Not to mention, this appears to be quite a widely planted tree, but also grows naturally especially near the coast.
One may of course mistake this for the non-native Neem tree of which the leaflets bear much resemblance, but the Neem tree is much less commonly seen, and the leaves are only one-times pinnate.
The Aglaias and Dysoxylums are typically pinnate-leaved trees, often with a terminal leaflet and the other leaflets arranged opposite to each other along the compound leaf rachis, but note that there are exceptions to the terminal leaflet, opposite-leaflet pairing rules (See later on the section “Rule Breakers”).
One of the first ways to distinguish the very similar looking Aglaia and Dysoxylum is to look for scales on the leaf or sometimes on the midrib of the leaflets, which will be present in Aglaia but not in Dysoxylum.
Aglaia elaeagnoidea – has bronzey-silvery scales on the leaves (both upper and lower). It also probably has the smallest leaflets amongst the FNQ Aglaias.
Aglaia meridionalis – beautiful tree with the leaf rachis having dense brown-red tomentum, and the leaflets underside having brownish scurf.
Aglaia sapindina – The specific epithet probably alludes to the resemblance of the leaf venation to members of the Sapindaceae. If you have seen a few Sapindaceae like lychees, rambutans etc you might agree.
Whole leaves of 6 common Dysoxylum species from Wet Tropics rainforest Left: Dysoxylum gaudichaudianum
Middle: D. arborescens (top); D. papuanum (middle); D. alliaceum (bottom)
Right: D. pettigrewianum sapling leaves (top); D. parasiticum (bottom)
Dysoxylum arborescens – fresh-green and somewhat shiny leaflets which are smooth on both sides, the terminal leaflet having the longest stalk. The compound leaf stalk is slightly winged from the point of attachment to the stem to the first pair of leaflets.
Dysoxylum gaudichaudianum has by far one of the largest leaves of the native Dysoxylums. They have very large and conspicuously uneven-based leaflets, and the lowest most leaflets are fatter and shorter than the ones further along the rachis. The leaflets have a soft dull green look and seems to have a raised midrib.
Dysoxylum mollissimum subsp. molle – oblong shaped leaflets. Lotsa leaflets, sometimes ~11 but sometimes like maybe more than 20 sometimes. Crushed twigs have somewhat of an onion/shallot smell. The leaflets often have strongly uneven bases.
Dysoxylum papuanum – probably the easiest Dysoxylum to recognize. Leaflets are somewhat light green and thinner than the other Dysoxylums.
Dysoxylum parasiticum – 13-20 leaflets which are hairy on the underside. The compound leaf stalks and twigs have rusty “pores”.
Dysoxylum pettigrewianum – largish oblong shaped leaflets. Most distinctively, the rachis from the base to the first pair of leaflets are sort of flat on the top side, with an almost imperceptible wing that extends to onto the twigs. In the forest, mature individuals are readily identified by the gigantic spur buttresses.
Dysoxylum setosum – This species can be recognized by the uneven-based leaflets and the very coarse venation on the undersides of the leaflets. “Hairy armpits” are visible at the junction of the midrib and nerves.
Synoum glandulosum – The stalks of the leaflets somewhat coloured, especially the terminal leaflet stalk in young leaves. Leaves have distinctive hairy domatia.
Toona ciliata – When well formed and well developed, this tree has ovate leaflets with an uneven base. Otherwise resembles Ganophyllum falcatum (Sapindaceae) and Euroschinus falcatus (Anacardiaceae)
Dysoxylum alliaceum – has the typical traits such as alternate compound leaves but quite non-descript other than the fact that it has a somewhat garlic-like smell when the twigs are broken. It also doesn’t have the terminal leaflet typical of other Dysoxylums
Dysoxylum klanderi – instead of a terminal leaflet, the compound leaf of this species ends off with a knob. I haven’t seen this yet so will update as I find one.
Dysoxylum latifolium – This species looks more like a member of the Sapindaceae due to it’s alternate leaflets, making it one of those species that you ‘know when you know’. The leaflets are somewhat glossy green on the underside and a only bit lighter in shade compared to the upperside. The midrib is raised on top.
Dysoxylum oppositifolium – this species is in many ways a rule breaker. For one, it has opposite leaves, and then it doesn’t have a terminal leaflet. In this respect it looks like a Flindersia, but of course there is no citrusy smell when plant parts are crushed and no oil dots in the leaves. However, this species has very interesting secondary veins which come off the midrib at almost 90 degrees, and is accompanied by a hairy armpit at almost every vein coming off the midrib. This latter trail is easily observable standing under the tree.