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.

Wattles are native to Australia. Of those species established in California, we have just about all (~14) of them in the bay area. The Jepson key is fairly straightforward, so I won’t bother to replicate the entire 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

cootamundra wattle
Acacia baileyana

2-pinnate leaves
2–5 pairs of 1st-order leaflets, 10–28 mm
8–24 pairs of 2nd-order leaflets, 3.5–7.5 mm

simple leaves

sydney golden wattle
Acacia longifolia

simple leaves, 5–15 cm long, with 2–4 longitudinal veins
flowers in 2–5 cm spikes (not round heads)
common

blackwood
Acacia melanoxylon

simple leaves, 4–14 cm long, with 3–5 longitudinal veins

leaves on young branches or mature leaf tips may be 2-pinnate

inflorescence a raceme of 2–8 heads
fruit 5–15 cm long, 0.4–0.8 cm wide, curved, twisted, glabrous
very common, especially in the outer coastal range

Edibility: Not all species have been tested for safety. All tested species contain trypsin inhibitors in the seeds, which prevent digestion of protein. Roasting the seeds improves their digestibility. [source]

5 observed taxons / 1 key

Chris’s observations: 22 (18 are research grade)

Locations:

Edgewood County Park & Natural Preserve: 7
Henry Cowell Redwoods SP: 2
Kauai, HI: 2
Waterdog Lake & Open Space: 2
Coyote Hills RP
Dimond Canyon Trail, Oakland
Don Edwards National Wildlife Refuge
Jacks Peak CP
Joaquin Miller Park, Oakland
San Pedro Valley CP
Sibley Volcanic RP
Sweeney Ridge National Recreation Area
Ulistac Natural Area, Santa Clara

Months:

Feb.: 2
Mar.: 6
Apr.: 0
May: 2
Jun.: 3
Jul.: 2
Aug.: 1
Sep.: 3
Oct.: 1
Nov.: 2

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Taxon info: iNaturalist – Calflora – Jepson eFlora – FNA

Bay Area species: iNaturalist – Calflora