Ionactis

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Genus of flowering plants in the family Asteraceae

title: "Ionactis" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["astereae", "asteraceae-genera", "flora-of-northern-america"] description: "Genus of flowering plants in the family Asteraceae" topic_path: "general/astereae" source: "https://en.wikipedia.org/wiki/Ionactis" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of flowering plants in the family Asteraceae ::

|image = Ionactis linariifolia illustration.svg |image_caption = Flaxleaf whitetop aster (Ionactis linariifolia) |display_parents = 3 |parent_authority = G.L.Nesom |taxon = Ionactis |authority = Greene |synonyms_ref = |synonyms = * Aster subgenus Ianthe (Torr. & A.Gray) A.Gray

Ionactis, common name stiff-leaved asters or ankle-asters, is a small genus of plants belonging to the family Asteraceae. These aster-like plants are endemic to North America (Canada and the United States). One species is widespread across much of the eastern half of the continent, while two others are rare endemics with very restricted ranges (see below).

The generic name, Ionactis, is derived from the Greek words "ion," meaning "violet" and "aktis" meaning "ray." This is in allusion to the ray florets, frequently pale purple in this genus.

Ionactis was classified as a separate genus by Edward Lee Greene in 1897 with the species Ionactis linariifolia, which had been classified by Carl Linnaeus as Aster linariifolius. The species of Aster (in a strict sense) are now restricted to Eurasia.

The stiff-leaved Asters are perennial herbs with numerous green stems, about 2,5 cm long (rarely 10 cm), usually in a tussock. The spatulate leaves are small, stiff, sharply ascending and thick about the stem. The upper leaves are much smaller than the lower. Yellow-orange resin droplets form on the leaves of the Red Rock Canyon Aster (Ionactis caelestis).

The involucral phyllaries (bracts under the flower head) are narrow and overlapping. They have, along the midrib, a narrow zone containing chlorophyll. The silky-hairy, fusiform achenes form a crown with a double pappus in two series, the inner one with long, barbellate bristles, the outer one with short bristles or minute scales.

The small flower heads grow solitary or sometimes in a cluster at the end of the stems. The 10–24 fertile ray florets are nearly white, blue to pink, lavender, purple or blue violet. The sterile disc florets are yellowish. The peduncles are nearly naked.

They have a chromosome base number of x = 9.

; Species

References

References

  1. 1913 illustration from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York. Vol. 3: 444.
  2. [http://dixon.iplantcollaborative.org/CompositaeWeb/default.aspx?Page=NameDetails&TabNum=0&NameId=b645090d-2659-452c-8bf7-ce2d35a1ca34 Flann, C (ed) 2009+ Global Compositae Checklist ]
  3. [https://www.biodiversitylibrary.org/item/52470#page/271/mode/1up Greene, Edward Lee. 1897. Pittonia 3(17C): 245–246] entirely in English
  4. [http://www.tropicos.org/Name/40031247 Tropicos, ''Ionactis'' Greene ]
  5. Nesom, G. L. and T. J. Leary. 1992. A new species of ''Ionactis'' (Asteraceae: Astereae) and an overview of the genus. Brittonia 44: 247–252.
  6. [[Guy L. Nesom. Nesom, G.]] 1994. - Review of the taxonomy of ''Aster'' sensu lato (Asteraceae: Astereae), emphasizing the new world species. Phytologia 77:141-297.
  7. [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=116459 Flora of North America Vol. 20 Page 7,17, 82, Ankle-aster, ''Ionactis'' Greene]
  8. Xiang, C. & J.C. Semple. 1996. - Molecular systematic study of ''Aster'' sensu lato and related genera (Asteraceae: Astereae) based on chloroplast DNA restriction site analyses and mainly North American taxa. Pp. 393-423, in D.J.N. Hind & H.J. Beentje (eds.), Compositae: systematics. Proc. Intern.
  9. [http://www.theplantlist.org/tpl1.1/search?q=Ionactis The Plant List search for ''Ionactis'']
  10. [http://bonap.net/NAPA/TaxonMaps/Genus/County/Ionactis Biota of North America Program 2013 county distribution maps]

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astereaeasteraceae-generaflora-of-northern-america