Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

  • Up-to-date information about California vascular plants is available from the Jepson eFlora.


Elizabeth McClintock

Tree, shrub, armed or unarmed
Leaves even-2-pinnate or, if simple, true blades 0, petioles and midribs blade-like (comprising phyllodia), generally alternate, generally evergreen; axes with prominent raised glands or not
Inflorescence: heads, spheric, generally axillary, these solitary or in racemes or panicles, or flowers in spikes
Flower radial; sepals, petals inconspicuous; stamens many, conspicuous, exserted, free
Fruit generally dehiscent, sometimes tardily so, flat or ± cylindric
Species in genus: ± 1200 species: tropical, subtropical, especially Australia
Etymology: (Greek: sharp point)
Reference: [Whibley 1980 Acacias of South Australia; Clarke et al. 1989 Systematic Botany 14:549–564]
Australian species cultivated, sometimes naturalized and spreading in CA (seed arilled, stalk often elongated, encircing seed or not).


M. arabica (L.) Huds.


Annual glabrous to sparsely hairy
Stem generally sprawling, 1–4 dm
Leaf pinnate or subpalmate; stipules generally cut 1/4–1/2 width; leaflets generally 1–2.5 cm, widely obovate to obcordate, length ± = width, generally with a central dark spot
Inflorescence 2–4-flowered
Flower: calyx 2–2.5 mm; corolla 4–5 mm, yellow
Fruit coiled 4–6 turns, spheric or short-cylindric; prickles curved, hooked
Seeds few
Chromosomes: 2n=16
Ecology: Disturbed and agricultural areas
Elevation: < 2000 m.
Bioregional distribution: North Coast, North Coast Ranges, n Sierra Nevada, Central Western California, probably elsewhere
Distribution outside California: abundant in se US, elsewhere; native probably to Mediterranean


M. orbicularis (L.) Bartal.

Annual, ± glabrous
Stem spreading, 1–4 dm
Leaf: stipules generally divided nearly to base into a cluster of bristles; leaflets 1–1.5 cm, obovate
Inflorescence 1–3-flowered, generally open
Flower: calyx 2.5–3 mm; corolla 3–6 mm, yellow
Fruit coiled 3–5 loose turns, generally disk-like, papery; prickles 0
Seeds few
Chromosomes: 2n=16
Ecology: Uncommon. Disturbed areas
Elevation: especially < 500 m.
Bioregional distribution: California Floristic Province
Distribution outside California: sporadic elsewhere in US; native probably to Mediterranean
Probably not naturalized in CA.

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