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Extriplex E.H.Zacharias in Syst. Bot. 35(4): 850. 2010 sec. Zacharias & Baldwin 2010
  • 1. Kew WCVP (2019)
  • =Atriplex [unranked] Californicae Standl., N. Amer. Fl. 21: 44. 1916 syn. sec. Zacharias & Baldwin 2010
  • Atriplex subsect. Californicae (Standl.) S.L.Welsh in Rhodora 102: 424. 2000 ["2001"] syn. sec. Zacharias & Baldwin 2010


The two species of Extriplex are endemic to the California Floristic Province. Extriplex belongs to the Archiatriplex clade within Chenopodieae, formerly Atripliceae (Kadereit & al. 2010; see Zacharias & Baldwin 2010 for detailed information on the genus). Molecular and geographical evidence strongly supports the monophyly of Extriplex . The two species of Extriplex are morphologically divergent but the radicle of both points laterally, and thereby separates Extriplex from
the other genera of this clade, which have either radicles that point towards the base of the fruit (i.e. Proatriplex, Grayia, and Holmbergia) or radicles that point towards the style (i.e. Stutzia). Although Extriplex joaquinana (= A. joaquinana) has been included within the Atriplex patula complex (Hall and Clements 1923), molecular results supported by morphological
differences show that E. joaquinana is not closely related to A. patula and is sister to E. californica.


Ab aliis Atripliceae combinatione characterum differt: habitus herbaceus annuus vel perennis; anatomia foliorum non-Kranz; flores staminati perianthiis lobatis, lobis 4, staminibus 4, oppositis lobo perianthii; flores pistillati portati singulariter intra 2 oppositas bracteolas cum, bracteolis distinctis vel leviter connatis ad 1/2 longitudines earum, perianthiis nullis;
semina verticalia; radiculae lateraliter directae; distributio in Provincia Floristica Californica et Baja Californica.

Chromosome Numbers

Haploid and diploid counts are n = 9 (Nobs 1975) and 2 n = 18 (Ruas et al. 2001), respectively.


From other Atripliceae it differs by a combination of characters: habit herbaceous, annual or perennial; anatomy of leaves non-Kranz; staminate flowers with perianths lobed, with lobes 4, with stamens 4, with stamens each opposite a lobe of a perianth; pistillate flowers borne singly within
2 opposite bracteoles, with bracteoles distinct or slightly connate
to 1/2 their lengths, with perianths none; seeds vertical; radicles pointing laterally; distribution in California Floristic Province and coastal desert of Baja California.

Annuals or perennials, erect or spreading to decumbent, 1–10 dm high, monoecious. Stems sparsely to much branched, sometimes striate when young, becoming stramineous, initially farinose, glabrescent; branches erect or ascending, stout or slender, terete. Leaves solitary or crowded, few or numerous, alternate or the proximalmost opposite, sessile or petiolate, the petioles 5–25 mm long; blades 4–70 × 2–40 mm, deltoid to ovate-rhombic (sometimes subhastate) or lanceolate to elliptic, the bases attenuate or acute, the margins irregularly sinuate-dentate or entire, the apices obtuse to subacuminate, the surfaces green to grayish, farinose when young, glabrescent or becoming scurfy; anatomy non-Kranz.
Inflorescences mixed and axillary, or staminate and/or pistillate flowers (mostly) at branch tips in dense or interrupted spikes or panicles. Staminate flowers each associated with a bracteole; perianths 4-lobed, united in proximal 1/4–1/2, ca. 1 mm long, the lobes rounded-triangular, cucullate; stamens 4, each opposite a perianth lobe; filaments inserted on disc at
base, subulate; anthers not exserted. Pistillate flowers borne singly within 2, opposite bracteoles; perianths lacking; stigmas 2, filiform, exserted. Fruiting bracteoles accrescent, paired, enclosing 1 pistillate flower, distinct to connate in proximal 1/2, 3–4.5 × 2–3 mm, ovate to more or less round or deltate, the bases sessile, rounded, the margins entire, the apices acute
to acuminate, the surfaces densely scurfy, smooth or ribbed. Utricles not spongy, not falling at maturity, 1–2 × 1–1.5 mm, subglobose or laterally compressed; pericarps membranous, free from seed or slightly adherent; seeds vertical, smooth, black to dark-brown, shiny; seed coats hard; perisperm copious, farinaceous; embryos annular; radicles pointing

Distribution (General)

Extriplex is known only from the California Floristic Province (CaFP) and coastal desert of Baja California. It is found inland in California (Central Valley, valleys of inner coast ranges) and on sandy coasts, shrubland, and salt marshes from slightly north of San Francisco to Cedros Island, Baja California.


The generic name is derived from the Latin prefix ex (meaning beyond, on the outside) plus the generic name Atriplex , which is a Latinized form of the Greek ατραφαξυs. The two known species of this genus previously
have been included within Atriplex ; they are more closely related to exclusively C3 genera of American Atripliceae than to any Atriplex.


Species of Extriplex are disparate ecologically. Extriplex californica is often found in monotypic stands on sea bluffs, sandy coasts, crevices in sea cliffs, coastal strands, edges of coastal salt marsh, and coastal sage scrub, often on sandy soils. Extriplex joaquinana is found in alkali sink scrub or alkaline grasslands with Allenrolfea occidentalis Kuntze, Atriplex depressa Jeps., A. fruticulosa Jeps., Cordylanthus palmatus J. F. Macbr., Distichlis spicata (L.) Greene, Frankenia salina I. M. Johnst., Centromadia pungens (Hook. & Arn.) Greene, Hordeum depressum (Scribn. & J. G. Sm.) Rydb., Lolium multiflorum Lam., Salicornia spp., Spergularia macrotheca (Hornem. ex Cham. & Schltdl.) Heynh., and Suaeda moquiniana (Torr.) Greene.


Flowering April–November.