Leaf Structure of our Mimosas and Acacias
by Bob Harms (
)
The mimosa leaf (and that of many other legumes) is doubly divided (bipinnate), first into pairs of pinnae and in turn each pinna into pairs of leaflets. [Pinna, plural pinnae is from Latin pinna = penna 'feather', from which also our word 'pen.'] The picture below shows one leaf from each of our three mimosas. The number of pinna pairs are 7, 3, 2 respectively (each one is numbered). The number of leaflet pairs for the pinnae enclosed in yellow is 13, 5, 6 respectively.
By contrast the related Sophora affinis, Eve's Necklace (below), is compound pinnate - with leaflets alternate (not oppositely paired) and an odd leaflet at the end.
Plant Resource Center Home Page — Flora of Texas
— Mimosa