Dysphania
Prodr., 411. 1810.
Herbs, annual or short-lived perennials, covered with stalked glandular trichomes, sometimes in combination with subsessile glands and/or uniseriate multicellular trichomes, sometimes glabrescent (rarely farinose), usually aromatic (or malodorous to some people). Stems erect, ascending, decumbent, or prostrate, branched (rarely ± simple), not jointed, not spiny, not fleshy. Leaves alternate, petiolate (distal leaves sessile in sect. Adenois); blade linear, lanceolate, oblanceolate, ovate, or elliptic, often pinnately lobed, base cuneate to truncate, margins entire, dentate, or serrate, apex obtuse, acute, attenuate, or acuminate, mucronate. Inflorescences terminal, loosely flowering, simple or compound cymes or dense axillary glomerules; bracts absent, but glomerules often subtended by reduced leaves (sometimes referred to as “leaflike bracts”). Flowers bisexual or rarely unisexual (at least functionally); perianth segments 1–5, connate basally to ± distinct, or fused to form sac surrounding fruit; stamens 1–5; ovary superior; styles 1–3, stigmas 1–3, filiform. Fruiting structures: achene often enclosed in perianth, pericarp adherent or nonadherent, membranaceous. Seeds horizontal or vertical, reddish-brown or black, subglobose to lenticular; seed-coat smooth to rugose; embryo annular or incompletely annular, surrounding copious farinose perisperm.
Contents
Distribution
Worldwide, mostly tropics, subtropics, warm-temperate zones
Discussion
Species ca. 32 (10 in the flora).
The generic name Dysphania traditionally was applied to seven to ten species endemic to Australia (P. Aellen 1930, 1930b; A. J. Scott 1978b; P. G. Wilson 1983, 1984, 1987). Placement and rank of this taxon have ranged from a mere section in Chenopodium (P. Aellen 1930, 1930b) to the sole genus of a separate family Dysphaniaceae, or a representative of Illicebraceae. Dysphania’s close affinity to “glandular” species of Chenopodium sensu lato is now evident (P. Aellen 1930, 1933, 1960–1961; T. Eckardt 1964b, 1967, 1967b, 1968, [1969]; T. J. Mabry and H.-D. Behnke 1976; F. A. Pax and K. Hoffmann 1934b; A. J. Scott 1978b; P. G. Wilson 1983, 1984, 1987).
Here the genus Dysphania is accepted in an expanded circumscription (S. L. Mosyakin and S. E. Clemants 2002), including all other “glandular” taxa previously treated in Chenopodium subg. Ambrosia A. J. Scott, or segregated in genera such as Roubieva Moquin-Tandon, Teloxys Moquin-Tandon, and Neobotrydium Moldenke. In its traditional circumscription Dysphania has no distinctive characters clearly separating it from those other “glandular” chenopods.
Presence of glandular trichomes seems to be a character of high phylogenetic and taxonomic importance in Chenopodiaceae, in which types of trichomes were used for delimitation of genera, tribes, and even subfamilies. This character seldom fails, even if there are some parallel evolutionary trends present. R. C. Carolin (1983) suggested that Chenopodieae with glandular hairs probably separated from Chenopodieae with bladder hairs even at a more basal (earlier) phylogenetic level than the point of divergence of the latter from Atriplicinae. Chenopodium species with bladder hairs (“mealy chenopods”) are probably more closely related to Atriplex and its satellite genera than to “glandular chenopods.” P. G. Wilson (1984, 1987) came to the same conclusion.
W. A. Weber (1985) adopted the name Teloxys Moquin-Tandon for the group of “glandular” taxa and transferred several species of “glandular” Chenopodium to Teloxys. The latter was published simultaneously with Roubieva, and thus, if only these two generic names are considered, Weber’s choice should stand. However, the generic name Dysphania predates both Teloxys and Roubieva, and “...[I]f Teloxys, Orthosporum, and Dysphania are amalgamated then the oldest name Dysphania should be adopted” (P. G. Wilson 1987).
Selected References
Keys
Key to the Sections and Subsections of Dysphania
| 1 | Seeds vertical | Dysphania sect. Orthospora |
| 1 | Seeds mostly horizontal (sometimes vertical in sect. Adenois) | > 2 |
| 2 | Flowers in dense glomerules arranged in spicate or paniculate inflorescences | Dysphania sect. Adenois |
| 2 | Flowers solitary or in few-flowered glomerules arranged in lax cymose inflorescences [6b. Dysphania sect. Botryoides] | > 3 |
| 3 | Leaf blades linear, narrowly lanceolate, or narrowly oblanceolate, margins unlobed; terminal branches of inflorescence usually bristle-tipped | 6b.Dysphania subsect. Teloxys |
| 3 | Leaf blades lanceolate to ovate or elliptic, margins lyrate-sinuate or pinnatifid (rarely unlobed); terminal branches of inflorescence usually ending in glomerules | > 4 |
| 4 | Perianth segments not tuberculate | 6b.Dysphania subsect. Botrys |
| 4 | Perianth segments often with single subterminal tubercle. | 6b.Dysphania subsect. Incisa |
Key to the Species of Dysphania
| 1 | Seeds vertical | > 2 |
| 1 | Seeds mostly horizontal (vertical in D. chilensis, sometimes vertical in D. ambrosioides and D. anthelmintica) | > 5 |
| 2 | Perianth urceolate, perianth segments connate almost to top, enclosing fruit; leaf blades with margins deeply pinnatifid to pinnatisect | Dysphania multifida |
| 2 | Perianth segments connate well below middle, hardly enclosing fruit; leaf blades with margins coarsely sinuate-dentate with obtuse lobes [6c. Dysphania sect. Orthospora] | > 3 |
| 3 | Perianth segments rounded abaxially | Dysphania pumilio |
| 3 | Perianth segments keeled or crested | > 4 |
| 4 | Perianth segments keeled, not crested; leaf blades ovate | Dysphania carinata |
| 4 | Perianth segments keeled and crested; leaf blades elliptic or ovate | Dysphania cristata |
| 5 | Flowers in dense glomerules arranged in spikes or panicles [6a. Dysphania sect. Adenois] | > 6 |
| 5 | Flowers solitary or in few-flowered glomerules arranged in lax cymose inflorescences [6b. Dysphania sect. Botryoides] | > 8 |
| 6 | Inflorescences leafless (glomerules without subtending leaves throughout inflores- cence, or subtending leaves very small, shorter than glomerules) | Dysphania anthelmintica |
| 6 | Inflorescences foliose to top (glomerules with reduced leaflike bracts) | > 7 |
| 7 | Leaf blades mostly ovate, oblong-lanceolate, or lanceolate, margins entire, den- tate, or laciniate, usually copiously gland-dotted but not villous | Dysphania ambrosioides |
| 7 | Leaf blades lanceolate, margins shallowly dentate to sinuate-pinnatifid, villous and gland-dotted | Dysphania chilensis |
| 8 | Leaf blades linear, narrowly lanceolate, or narrowly oblanceolate, margins unlobed; terminal branches of inflorescence usually bristle-tipped [6b.3. Dysphania subsect. Teloxys] | Dysphania aristata |
| 8 | Leaf blades lanceolate to ovate or elliptic, margins lyrate-sinuate or pinnatifid (rarely unlobed); terminal branches of inflorescence usually ending in glomerules | > 9 |
| 9 | Perianth segments not tuberculate [6b.1. Dysphania subsect. Botrys] | Dysphania botrys |
| 9 | Perianth segments with single subterminal tubercle [6b.2 Dysphania subsect. Incisa] | Dysphania graveolens |