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years, in June, festooned richly with drooping clusters of fragrant, white, 
pealike flowers. Another similarity is that both woods contain a yellow 
dye. Its pealike flowers help reveal yellowwood as a member of one 
subgroup of the Legume Family (Fabaceae). That this tree is a legume is 
revealed further by the pinnately compound leaves (each leaf looking 
like a short branch with several small leaves along it) having “pulvini”. A 
pulvinus is a small thickened joint at the base of each leaf and at the bases 
of its subdivisions. 
Pulvini act like tiny muscles that let the leaves droop at night and 
stiffen by day. Virtually all legumes have pealike or beanlike, sometimes 
woody, pods. Watch for such pods around the Garden and around town, 
and you may thus recognize the following as legumes: sophoras, red- 
buds, honey locusts, black locusts, mimosas (genus Albizia, not Mimosa), 
Kentucky coffeetrees, and wisterias. 
The name yellowwood comes from a yellow dye obtained from the 
wood and once thought to have commercial potential. Cladrastis comes 
from Greek for “brittle branches”, and kentuckea refers to the place of 
discovery. 
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