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Chrysothamnus is Greek for "golden bush". |
Chrysothamnus
depressus (Low Rabbitbrush) Foothills. Open woodlands, meadows. Summer, fall. This low shrub (hence "depressus", Latin for "flattened or pressed down"), can be uncommon to abundant. Professional floras indicate that the plant is no more than 18 inches tall, but plants in the two photographs immediately above are 20 to 25 inches tall, and the plant is commonly 20 or more inches tall in the Carpenter Natural Area. Although Chrysothamnus depressus flowers are small (about 9-15 mm in length), they are about twice as long as as those of C. greenei and C. viscidiflorus, two other Chrysothamnus in the Four Corners area. When C. depressus occurs in large numbers (as it commonly does) it is a conspicuous and attractive shrub -- even in its fall color of golden brown. Chrysothamnus depressus was found for science in the in 1830s by Thomas Nuttall and he named and described it in 1848. Nuttall only indicated that he collected it in the "Rocky Mountains". |
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Chrysothamnus
depressus (Low Rabbitbrush) Foothills. Open woodlands, meadows. Summer, fall. The phyllaries are sharply pointed and strongly ribbed ("keeled") giving the flower head a prickly and angular appearance. They are in 4–6 series, in 5 strong vertical ranks and have obvious mid-nerves. Once the bright yellow flowers open (second photograph at left), the angularity is added to by the sharply pointed lobes of the corolla. The third photograph at left shows the silky pappus hairs which are long (5.5 to 7.5 mm), numerous, and quite evident after the flowers have faded. |
Chrysothamnus
depressus (Low Rabbitbrush) Foothills. Open woodlands, meadows. Summer, fall. The photographs above and at left show the young spring leaves, thin gray-white leaning flower stems from last year, and older thick mature silvery gray stems of many years of growth. (The large piece of dead wood slanted from the bottom left of the above photograph is from Artemisia nova). When first emerging, young leaves appear to be fascicled (bundled) but the stems will elongate and the leaves will be alternate and nearly vertically pressed against the stems, as in the photograph immediately below. Mature leaves are frequently similar to the phyllaries in their pointed (acute) tips. They have evident mid-nerves, are linear to oblanceolate or narrowly oblong, 7–30 mm × 1.5–7 mm, flat to keeled, and although they may be glabrous, they are frequently densely covered in fine, short hairs (i.e., "puberulent") and often are glandular puberulent. Use a hand lens to see the fine hairs. |
Chrysothamnus
greenei (Greene's Rabbitbrush) Foothills. Shrublands, woodlands, meadows. Summer, fall. |
Chrysothamnus
greenei (Greene's Rabbitbrush) Foothills. Shrublands, woodlands, meadows. Summer, fall. |
Chrysothamnus
greenei (Greene's Rabbitbrush) Foothills. Shrublands, woodlands, meadows. Summer, fall. Although Chrysothamnus greenei is uncommon in the Four Corners area, when it is found it is often abundant and it gives a golden glow to the area from its numerous plants with innumerable flowers. Chrysothamnus greenei typically grows to no more than 50 cm tall (about 20 inches), but the plants shown on this page are about 60 cm tall and many in the Carpenter Natural Area of Cortez exceed 50 cm. Disk corollas are no more than 5.5 mm long. Flower clusters are numerous, each with 4-5 florets (small flowers), and the heads are crowded atop new twig growth that is light green. This tops the previous few years of twig growth that is white and peels off in small scales when you scratch the surface. Older twigs become gray and fibrous on the surface. Leaves are quite narrow; as shown here they are just a millimeter wide but they may be up to 2 mm wide. They can be from 10 to 40 mm long (as shown here about 22 mm long) and sometimes the leaves have a twist to them, similar to the twisted leaves of C. viscidiflorus shown below. Leaves are glabrous but may be very finely ciliate margined. Much of the plant is covered with a resinous exudation that has a very pleasant smell. Chrysothamnus greenei is very similar to Chrysothamnus viscidiflorus (shown below) and the two are difficult to tell apart unless one examines the flower heads with a magnifying glass, or if they are fully mature plants. Then C. viscidiflorus is easier to spot as it is up to twice as tall as C. greenei. See below for other differences in the two species. Chrysothamnus greenei was at first named Bigelovia greenei by Asa Gray in 1876 from a collection made by Edward Greene in Colorado in 1872. Greene gave the plant its present name in 1895. Greene was a respected collector, botanical author, and preacher. (Click for more biographical information about Greene.) |
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Chrysothamnus
greenei (Greene's Rabbitbrush) Foothills. Shrublands, woodlands, meadows. Summer, fall. Phyllaries are unequal in length, in The linear leaves are sometimes sulcate. Glistening of the leaves and phyllaries is evidence of the numerous glandular hairs which impart a very sweet smell.
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Chrysothamnus viscidiflorus variety viscidiflorus (Sticky Rabbitbrush) Semi-desert, foothills, montane. Woodlands, meadows, disturbed areas. Late summer, fall. |
Chrysothamnus viscidiflorus variety viscidiflorus (Sticky Rabbitbrush) Semi-desert, foothills, montane. Woodlands, meadows, disturbed areas. Late summer, fall. |
Chrysothamnus viscidiflorus variety viscidiflorus (Sticky Rabbitbrush) Semi-desert, foothills, montane. Woodlands, meadows, disturbed areas. Late summer, fall. Chrysothamnus viscidiflorus blooms in late summer-to-fall with an abundance of tiny flowers clustered into a golden-yellow glow. The shrub is usually evenly rounded, it is typically several feet tall (but may be over three), the base of the flower cluster is commonly sticky (hence the Latin "viscidiflorus", meaning "sticky flower"), its leaves are commonly twisted into a gentle spiral, and the stems are smooth without a whitish, hairy coating. Ericameria nauseosus, a very common species with which C. viscidiflorus is commonly confused, has white-hairy stems and often grows five to six feet tall and round. The lumpy projections beneath the golden-yellow flower heads are the phyllaries that cover the incipient flowers and then open and subtend the flowers. The shape, arrangement, and color of phyllaries varies from one member of the Sunflower Family to another and thus these characteristics help distinguish species. The phyllaries of Chrysothamnus viscidiflorus are variable; they may be overlapping in a vertical line (as shown here) or they may spiral; there may be anywhere from 12 to 24 phyllaries; their shape varies significantly; they may be hairy or not; their tips may be pointed or rounded; etc. The physical characteristics of C. viscidiflorus phyllaries are quite similar to those of C. greenei shown above and it is often difficult to distinguish between the two species -- especially when C. viscidiflorus is young. They differ as follows: 1) C. viscidiflorus commonly grows to a meter tall and even to 1 1/2 meters tall; C. greenei grows to a bit over half of a meter tall. 2) C. viscidiflorus leaves are linear to lanceolate, 10–75 long × 0.5–10 wide mm and they have a visible mid-vein and two or four side veins; C. greenei leaves are linear-filiform, 10–40 long × 0.5–2 wide and they have one faint mid-vein, often sulcate, i.e., grooved. 3) C. viscidiflorus phyllaries have acute to obtuse tips, mid-veins usually visible (at least distally); C. greenei phyllaries have acuminate tips, mid-veins rarely visible and the tip is often drawn out very finely. 4) C. viscidiflorus flower heads are up to 7 cm wide; C. greenei flower heads are up to 4 cm wide. Welsh notes in his A Utah Flora that C. viscidiflorus and C. greenei do hybridize, forming plants with intermediate characteristics. The first specimens of C. viscidiflorus were collected by David Douglas along the Columbia River in 1826 and the plant was first named Crinitaria viscidiflora by William Hooker in 1834. In 1841 Thomas Nuttall gave the plant its present name. However, the Philadelphia Herbarium has a collection by Meriwether Lewis of this species dated May 6, 1806. Click to read why Lewis' collection is not considered the type. "Viscidiflorus" means "sticky flowered", but I often find that C. greenei is also sticky from sweet smelling glandular secretions. |
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Chrysothamnus viscidiflorus variety viscidiflorus (Sticky Rabbitbrush) Semi-desert, foothills, montane. Woodlands, meadows, disturbed areas. Late summer, fall. |
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Chrysothamnus viscidiflorus variety viscidiflorus (Sticky Rabbitbrush) Semi-desert, foothills, montane. Woodlands, meadows, disturbed areas. Late summer, fall. Leaves of this variety of C. viscidiflorus are commonly twisted and glabrous (or sometimes ciliate). |
Range map © John Kartesz,
County Color Key
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Range map for Chrysothamnus depressus Range map for Chrysothamnus greenei Range map for Chrysothamnus viscidiflorus |