Know Your Natives – Western Daisy

Western Daisy (Astranthium ciliatum) (formerly Astranthium integrifolium*), of the Aster (Asteraceae) family, is an annual species with daisy-like flower heads. In the U.S., it is found in Arkansas, Oklahoma, Texas, southern Nebraska and southwestern Missouri with greatest concentrations in eastern Oklahoma and western Arkansas. The genus Astranthium comprises about a dozen species from the southern U.S. and Mexico, with only a single species in Arkansas, reported from the Ozarks, the Arkansas River Valley and the Ouachitas. Another common name is Comanche western daisy. The genus name is from the Greek for “star” referring to the star-like flower heads as seen from above. The specific epithet, also of Greek origin, means “fringed with hairs” in reference to the plant’s pubescence. Western daisy is found primarily in full or partial sun in sandy, clay or loam soils of grasslands, glades, and open deciduous woods mostly in lowlands. Plants have short, tough tap roots or multiple, radiating, near-surface roots up to 2 inches long.

Western daisy is a small plant that germinates in the fall into winter to form a flat-lying rosette of basal leaves, up to several inches across. Basal leaves, which have entire (smooth) margins, have an oval shape with a gradually narrowed base (spatulate) and long hairs on the upper surface. In late winter, ascending leaves, attached to a rudimentary main stem, appear from the center of the basal leaves as the basal leaves begin to fade.

Western Daisy - Astranthum ciliatumPhoto 1: In mid-March, new leaves appear as the winter leaves fade. Note pubescence.

Stems, which are light green, are slender, with three to four slight ridges that connect with petiole-stem junctions. Faint reddish shading may be present on stems, especially on ridges. The single main stem typically has secondary stems that arise from lower leaf axils at about 35 degrees off the main stem.

In less desirable sites (excessive shading, crowding, etc), plants may remain small with no or few secondary stems. In more desirable sites, secondary stems become dominant and, in turn, may bear stems that arise from their upper leaf axils. Secondary stems, which are fairly straight, are erect on smaller plants and spreading to ascending on larger plants. Stems are covered by soft hairs.

Western Daisy - Astranthum ciliatumPhoto 2: In less desirable sites, plants remain small with limited secondary stem growth. White flowers shown with the western daisies are of long-flower cornsalad (Valerianella longiflora).

Alternate stem (cauline) leaves have the same light green color on upper and lower sides as the stems; however, lower sides are slightly shinny. Blades of lower cauline leaves, to 1¼ inch long and ½ inch wide, have an elongate oval shape that is entire and widest at mid-blade, becoming gradually more narrow toward their sessile bases (oblanceolate). Blades of upper cauline leaves become increasingly smaller and more narrow up-stem, with more pointed apices (lanceolate) and while remaining sessile. Lowermost leaves have relatively long pubescence on upper blade surfaces and margins (ciliate) and have glabrous lower surfaces. Spacing of cauline leaves varies with the greatest spacing being at the lowermost portions of stems where spacing may be up to 1¾ inches while other leaves may be spaced at ¼ inch. Leaf-stem junctions are at about 35 degrees from which point lower leaves recurve downward while upper leaves extend mostly outward.

The primary inflorescence of western daisy, at apices of stems, consists of single composite flower heads on long peduncles. Peduncles, measured from the base of the flower head to the uppermost cauline leaf, vary from short (1 inch or less) to long (to 3 inches). Peduncles have the same appearance as stems. As peduncles grow and strengthen, flower head buds are at first upright, then droop and then become upright again at anthesis. A plant’s first flower head to reach anthesis, regardless of plant size, is that single head at the apex of the main stem.

Western Daisy - Astranthum ciliatumPhoto 3: In more desirable sites, as shown by this single plant, secondary stems become dominant. Flower head at apex of main stem can be seen mostly hidden at center of plant. Note drooping flower head buds.

Western Daisy - Astranthum ciliatumPhoto 4: Display of flower heads from buds (lower left) to past-anthesis (lower center).

Flower heads, up to about an inch wide, have up to about 20 pistillate ray florets and numerous bisexual disk florets (radiate flower heads). Flower heads have a slightly domed center and rounded (hemispheric) involucres. Strap-like ligules of the ray florets, about ¼ inch long, have rounded to notched apices and constricted bases. Ligules typically overlap, but may also be spaced slightly apart. The constricted bases of the ligules are not especially visible except when ligules are spaced apart. Ligules are typically light lavender, but may be white. Lavender ligules may or may not have white coloration near their bases, with the color change being gradual or sharp. Tiny disk florets, yellow with yellow pollen, have five triangular spreading lobes on the rim of a short corolla tube set on a green ovary. Exserted anthers, cohering into a short tube, make pollen available to insects when the style, like a plunger, pushes through their tube, depositing the pollen on the surface of the disk. Involucres, composed of about 20 thin, lanceolate, green, equal-length and appressed phyllaries, are slightly overlapped along their translucent edges.

Western Daisy - Astranthum ciliatumPhoto 5: Disk florets have five lobes on their corollas and anthers fused into a tube, as shown by the outer ring of florets. Ligules have constricted bases and rounded to notched apices. The disks of composite heads typically flower from the outside in toward the center. Here the head is just getting started. Notice how immature the central disk floret buds are compared to those near the perimeter.

Western Daisy - Astranthum ciliatumPhoto 6: Involucre composed of lanceolate, slightly overlapping phyllaries. Peduncle, slightly ridged and pubescent, has same appearance as stems. Spiders and pollinating insects often have encounters on flower heads.

With fertilization, each floret produces a single one-seeded achene of two fused carpels (the two halves of a typical sunflower seed wall), surmounted by a ring of hairs at the top (pappus). With fruit (achene) dispersal, a conic, pitted receptacle remains.

  • Western daisy (Astranthium ciliatum) has been assigned to various species and subspecies over time. The most recent reassessment defines western daisy (Astranthium ciliatum) as being found west of the Mississippi River and eastern daisy (Astranthium integrifolium) as being found east of the Mississippi River.

Footnote: There are several other species of composites in Arkansas, representing various genera, that may also have “daisy” in their common names.

Article and photographs by ANPS member Sid Vogelpohl

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