Mem. Amer. Acad. Arts, n. s.4: 71. 1849
sw United States, Mexico, South America (Colombia, Peru).
Species 6 (5 in the flora).
Molecular evidence from nuclear ribosomal DNA ITS and ETS sequences has indicated that Psilactis is closely related to Symphyotrichum (J. C. Semple et al. 2002; D. R. Morgan 1997, 2003).
Psilactis odysseus (G. L. Nesom) D. R. Morgan is the only species of the genus that does not occur in the flora area. It is found in the Mexican states of Nuevo León and Tamaulipas and is distinguished from the other five species by being a monocephalous, rhizomatous perennial.
Arida crispa and A. coulteri have been placed in Psilactis in the past because they have epappose ray florets (B. L. Turner and D. B. Horne 1964). They were placed in what is now Arida by R. L. Hartman (1990) because they produce flavones and have chromosome numbers of n = 5.
|1||Involucres 2–4 mm; ray laminae 1–4 mm||Psilactis brevilingulata|
|1||Involucres 4–8 mm; ray laminae 4–15 mm||> 2|
|2||Phyllaries 0.3–0.7 mm wide; involucres broadly turbinate||> 3|
|2||Phyllaries 0.6–1.2 mm wide; involucres hemispheric||> 4|
|3||Disc cypselae glabrate or glabrous, 2–3 mm, length 1.5–2 times ray cypselae||Psilactis heterocarpa|
|3||Disc cypselae appressed-hairy, 1.5–2.5 mm, length 1–1.4 times ray cypselae||Psilactis tenuis|
|4||Bases of distal cauline leaves cordate to auriculate, clasping; involucres 5–8 mm; receptacles 4–6 mm diam||Psilactis gentryi|
|4||Bases of distal cauline leaves cuneate to slightly cordate, sometimes slightlyclasping; involucres 4–5 mm; receptacles 1.8–4 mm diam||Psilactis asteroides|
|Author||David R. Morgan +|
|Etymology||Greek psilos, bare, and actis, ray, alluding to epappose ray florets +|
|Illustrator||Bee F. Gunn +|
|Reference||morgan1993b + and turner1964a +|
|Synonym||Machaeranthera Psilactis +|
|Taxon name||Psilactis +|
|Taxon parent||Asteraceae tribe Astereae +|
|Taxon rank||genus +|
|Volume||Volume 20 +|