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(updated May 17, 2021)
Western Sunflower, Naked Sunflower
Helianthus occidentalis Riddell
Asteraceae (Sunflower Family)
(no photos available)
Helianthus occidentalis
Riddell, Western Sunflower, Naked Sunflower:
(Bayer Code:
not known; US Code:
not known)
·
U.S. native creeping perennial, rhizome-producing wildflower that grows
2-5 feet tall or more, usually with unbranched (except in upper portions during
flowering), nearly leafless, red-green to reddish stems; stems hairless to
slightly hairy
·
Leaves are opposite, often forming a basal semi-rosette due to short
internodes, in the first part of the growing season; leaves are oval to
lanceolate, usually smooth margined (sometimes with teeth on margins),
rough-textured, with stiff hairs and pointed leaf tip; three main veins on leaf
start at junction with petiole; leaves have a short petiole; flowering stem
leaves are absent or few and smaller than basal leaves
·
Head inflorescences are 1.5-2.5 inches in diameter, produced at stem
tips, with 8-14 yellow ray florets (“petals”) that are puckered where they join
the head, and 50 or more yellow disk florets
·
Bracts below the head are in overlapping rows, lanceolate, with
tapering, pointed tips; bract tips stand out from base of head; hairs line edges
of bracts
·
Flowering from mid-summer through autumn
·
Prefers dry, full-sun locations— pastures, prairies, rangeland, glades,
right-of-ways
·
The nearly-leafless flowering stems are unique to this perennial
sunflower; it may appear similar to prairie dock (Silphium
terebinthinaceum), but prairie dock has much larger and
broader leaves (12 inches long or longer) upright
PERENNIAL SUNFLOWERS:
·
Include
Ashy Sunflower,
Texas Blueweed,
Maximilian Sunflower,
Sawtooth Sunflower,
Western Sunflower,
Willowleaf Sunflower,
Jerusalem
Artichoke,
and other species
·
All are creeping perennial weeds that form rhizomes and/or creeping
roots that allow them to spread to form colonies with maturity
·
Most are palatable to livestock, except in fertile soils, where high
nitrate accumulation may cause poisoning, but may be seen as weedy in reduced
tillage crops
·
Once established, these species can be hard to
control, but
most
(not all) are not considered to be weedy
·
Most produce relatively tall (4-8 feet tall or more), unbranched, leafy
stems with linear, lanceolate to ovate/triangular, rough-textured leaves; upper
stem portions are usually branched with the onset of flowering, so that each
branch stem tip has a flower head
·
Flowers for most perennial sunflowers quite similar (with some
exceptions); they are in terminal clusters, flowering usually sometime from
mid-summer to late autumn, with yellow ray flowers and yellow to brown disk
flowers; total flower diameter is usually 2-4 inches
o
Perennial sunflower “flowers” are usually smaller
than annual sunflower “flowers,” such as with
Annual Sunflower (Helianthus
annuus) or
Prairie Sunflower
(Helianthus
petiolaris)
·
Usually, it is more of the stem and leaf characteristics that are used
to identify the different perennial sunflower species
·
Click on
links
of above individual plant names to see more information on each one
·
Most perennial sunflowers
are native plants that usually do not cause harm in grazing or haying situations
(maybe with the exception of Texas blueweed).
Perennial sunflowers
provide food and nectar for native insects (including bees and butterflies),
birds and other animals, and generally should not be killed indiscriminately.
Maintaining proper grazing
levels can often reduce their unwanted increase in pastures and rangeland.