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The
genus Heterotheca is complex and not completely understood. In
William Weber's words: "This group, centering around... Heterotheca
villosa, exhibits an enormous range of variability. Many
species and varieties have been proposed for what seem to be nodes of
stability within a mass of variable characters...." In early
editions of Colorado Flora: Western Slope, Weber listed four
species of Heterotheca. In the 4th edition published in 2012 he lists only the two: H. pumila and H. villosa.
In addition, Weber recognizes three more species, H. canescens, H.
foliosa, and H. latifolia on the Eastern
slope.
The Synthesis of the North American Flora and the Flora of North America recognize the following species of Heterotheca in the Four Corners area: H. fulcrata (uncommon in two counties), H. schneideri, H. subaxillariis (rare in one county), H. villosa, and H. zionensis. The 2020 major revision of the Heterotheca genus by Guy Nesom should be consulted for the most accurate view of the genus. "Taxonomic Summary of Heterotheca": Part 1, Part 2, Part 3, Part 4, Part 5. Heterotheca villosa is found in most counties of the Rocky Mountain states, including almost every county in Colorado. The species is highly variable with 9 varieties recognized nationally, 6 in Colorado, seven in New Mexico, 4 in Utah, and 4 in Arizona. Varieties differ from each other primarily on the basis of the amount and shape of hairs and the shape of the leaves. The two species of Heterotheca shown below spread easily and rapidly in warm dry exposed areas, H. schneideri in subalpine and alpine settings and H. villosa from the foothills to the subalpine. Both species form numerous, eye-catching symmetrical clusters five-to-twenty inches tall and several feet in diameter. An abundance of small, bright yellow flowers cover the plant from late spring through fall. Light and dark green to olive and sage green leaves frequently have a strong, pleasant, spicy pungency. In 1817 Alexandre Cassini gave the name "Heterotheca" to a new genus. "Hetero" is Greek for "varying" or "different" and "theca" for "case" or "box", referring to the different morphology of seeds produced by the ray and disk flowers of some Heterotheca species. This is an unusual and diagnostic characteristic, for many other Sunflowers produce identical seeds from both the outer ray flowers and the inner disk flowers. From Cassini's original French description of Heterotheca:
And with a bit of help from Google translations:
Present day Heterotheca experts Guy Nesom and John Semple also indicate that "Heterotheca" refers to the differing cypselae (achenes, seeds). Nesom: "the ray fruits are slightly larger and differently shaped than the disc fruits and they are epappose [without pappus hairs]" Semple indicates in the Flora of North America treatment of Heterotheca: "the ray cypselae are usually glabrous and lack pappi". Heterotheca villosa was first collected by Thomas Nuttall "on the Missouri" in 1811 while he was on an Aster expedition. The species was first named Amellus villosus by Frederick Pursh in 1814. Nuttall renamed the plant Chrysopsis villosa in 1836 and Shinners moved this species to the Heterotheca genus in 1951. The species is highly variable and has endured many name changes and many suggested divisions into a number of subspecies or varieties. For a considerable time, Heterotheca schneideri was identified as H. pumila, but Nesom's "Taxonomic summary of Heterotheca" in 2020, showed that H. pumila is found in the central and north central mountains of Colorado and the species in the southwest mountains is distinct from H. pumila. That species is now Heterotheca schneideri. For range maps, detailed descriptions, specimens, and photographs, see Part 4, pages 306-319 of Nesom's revision of Heterotheca. These two species have endured many name changes and various divisions, but the species ignore these human problems and always retain their eye-arresting beauty and their pungent-sweet aroma. |
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Heterotheca schneideri. Synonyms: Heterotheca pumila, Chrysopsis pumila. (Schneider's Golden Aster) Subalpine, alpine. Scree.
Late spring, summer, fall. As the photograph above indicates, Heterotheca schneideri likes rocky, sunny areas in the alpine and subalpine zones, but it is also found in open woods. It spreads easily and can line trails and cover steep mountainsides. The lower leaves of H. schneideri wither and remain on the plant into the next season. Flower heads are usually one per stem, numerous on each plant, and just above the pleasantly aromatic leaves. This can be an abundant plant near and above tree-line. Plants grow to over a foot tall and flower heads are typically a bit over an inch in diameter, up to twice as large as those of H. villosa. The specific epithet, "schneideri", was given by Asteraceae expert Guy Nesom in his major revision of the Heterotheca genus. "Schneideri" refers to Betty and Al Schneider, authors of this website. See part 4, pages 306-319 of the revision for the description of Heterotheca schneideri. |
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Heterotheca schneideri. Synonyms: Heterotheca pumila, Chrysopsis pumila. (Schneider's Golden Aster) Subalpine, alpine. Scree.
Late spring, summer, fall. |
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Heterotheca schneideri. Synonyms: Heterotheca pumila, Chrysopsis pumila. (Schneider's Golden Aster) Subalpine, alpine. Scree.
Late spring, summer, fall. Phyllaries are narrow, green (usually with red ("anthocyanic") tinges at the tips), and in 4-5 overlapping rows. Leaves are moderately to densely hairy. The central leaf vein is prominent and the leaf is highly reticulate. Notice also the two narrow, long, green bracts that subtend the flowerhead. Stems are often quite hairy and have long vertical ridges which have tinges of red. For a complete description of all Heterotheca species, see Guy Nesom's 2020 revision of Heterotheca. You will find H. schneideri described in part 4. Go to page 306. |
Heterotheca villosa. Synonym: Chrysopsis villosa. (Hairy Golden Aster) Semi-desert, foothills,
montane. Openings, disturbed areas. Late spring, summer, fall. Heterotheca villosa seeds itself and spreads beautifully and extensively on its own. It flowers from spring into late autumn. The top photograph shows a 30 foot diameter patch of Heterotheca villosa. The second photograph shows a single plant over 3 feet wide and 2 feet high. The third and fourth photographs above show a very old, woody Heterotheca villosa about 3 feet wide and nearly 2 feet tall. The plant is still quite healthy, as evidenced by the numerous dried flowers from the 2021 season and by its flowering into late November when the photographs were taken. |
Heterotheca villosa. Synonym: Chrysopsis villosa. (Hairy Golden Aster) Semi-desert, foothills,
montane. Openings, disturbed areas. Late spring, summer, fall. Heterotheca villosa is abundant not only in the foothills and mountains, but also in vacant lots, farmyards, and along roadsides. It needs little water, blooms from late spring through late fall, seeds itself readily (and spreads from roots), and has a marvelous spicy-sharp sage aroma. This is one of the easiest of native plants to have around your house. They are very hardy and will out-compete non-native weeds. I have many, many hundreds of these on my property. "Villosa" is Latin for "hairy", but as used in botany, the term refers to long, soft, unmatted hairs. |
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Heterotheca villosa. Synonym: Chrysopsis villosa. (Hairy Golden Aster) Semi-desert, foothills,
montane. Openings, disturbed areas. Late spring, summer, fall. Flowers are long-lasting and each plant will put out many dozens of flowers. After the initial spring flowering, each plant restores its energy, flowers again a few weeks later, and repeats this cycle until late fall. Basal leaves of H. villosa often persist green through the winter and begin growing again in the spring. H. villosa is a long-lived perennial so you will see it for many years in the same location. |
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Heterotheca villosa. Synonym: Chrysopsis villosa. (Hairy Golden Aster) Semi-desert, foothills,
montane. Openings, disturbed areas. Late spring, summer, fall. Leaf color variations, even in plants growing side by side, are very noticeable. |
Range map © John Kartesz,
County Color Key
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Range maps for Heterotheca schneideri and H. pumila. Heterotheca schneideri is found in 10 counties in the southwest corner of Colorado. Heterotheca pumila is found through the central mountains of Colorado and in northern New Mexico and southern Wyoming. The map immediately above is from Nesom, part 4, page 293. Range map for Heterotheca villosa |