wattles

genus Acacia

Member of legume family (family Fabaceae)
dicots (class Magnoliopsida)
flowering plants (subphylum Angiospermae)

Caution: There are other wild species of this genus not yet included in this guide.
Caution: The key to distinguish these species is not complete.

We have just about all (~14) California species in the bay area. The Jepson key is fairly straightforward, so I won’t bother to replicate the key here.

Key features:

simple leaves:

longer or shorter than 40 mm
stipular spines present or not
tip spine-like or not
with one prominent midvein or 2+
leaf shape
flowers in spikes or heads
leaves, stems resinous or not
shrub (spreading from base) or tree (generally with 1 trunk)

or 2-pinnate leaves:

2–5 pairs of 1st-order leaflets or 6+
twigs wingled or angled
2nd-order leaflets < 7 mm or ≥ 10 mm
leaf main axis with raised glands at each pair of 1st-order leaflets or also in between

glands are only on the adaxial (upper) surface of the axis
“in between” might just be a raised ridge between glands

2-pinnate leaves

silver wattle
Acacia dealbata

2-pinnate leaves
6–30 pairs of 1st-order leaflets, 15–55 mm
15–70 pairs of 2nd-order leaflets, 2–5 mm
leaf main axis with raised glands at each pair of 1st-order leaflets
twig angled (not winged)
common

black wattle
Acacia mearnsii

2-pinnate leaves
7–31 pairs of 1st-order leaflets, 15–70 mm
20–70 pairs of 2nd-order leaflets, 1.5–3.5 mm
leaf main axis with raised glands at most pairs of 1st-order leaflets and generally between
twig angled (not winged)
waif