Pods of M. borealis and M. texana (& M. aculeaticarpa)

by Bob Harms ()

M. texana	M. borealis
M. aculeaticarpa

When several pods of both M. borealis and M. texana are available, their relative differences are generally apparent. But a single pods alone may not suffice for field identification. Unless the pods are badly weathered (as is often the case in late summer) or poorly handled (e.g., by touching the base of the pod), examination under a microscope (20X) generally will reveal a number of distinctive features, even flower structure, since the dried flower generally persists around the base of the pod. (Cf. Flower Data from Mimosa Pods.)

Selected pod differences available to the naked eye are tabulated below (values based on Barnaby 1991).

Species	pods per cluster	pod length	pod width	color when ripe	base	replum
M. borealis	1-5	25-60 mm	6-10 mm	brown	stipitate(1)	stout, deeply constricted
M. texana	2-9	18-35	4.5-6	red-brown	subsessile(2)	shallowly constricted

(1)Having a stipe (supporting stalk).
(2)Nearly sessile (attached directly, without a stalk/stipe). In the top left photo red lines show that the gradual narrowing of the replum toward the base do not form a stipe.