WILDFLOWERS OF NEW MEXICO
Multiple 1–4-feet tall, leafy stems form rounded to arching, bushy plants covered with flat-topped to rounded arrays with 3–10 yellow flower heads per branch. The most widespread and common form, var. flaccidus, has a thick covering of white to gray-green, woolly hairs throughout, but var. monoensis is hairless; both have either 8 or 13 yellow ray flowers around a yellow disk.
FLOWER: April–September. Clusters of 3/4-inch wide (20 mm) flower heads on the stem tips have 8–13 narrow, yellow petal-like ray flowers 3/8–3/4-inch long (10–20 mm); var. monoensis has ±21 phyllaries and var. flaccidus has ±13 or ±21 phyllaries. Note the small leaf-like bractlets 1/2 the length of the phyllaries or longer beneath the flower head of the hairless var. monoensis. Bractlets absent or tiny in var. flaccidus.
LEAVES: Alternate, evenly distributed. Blades narrow, 1–4-inches long, with thread-like lobes along the midrib; surfaces either hairy or hairless depending on variety.
HABITAT: Dry sandy, rocky soils, grasslands, shrublands, roadsides, disturbed areas; desert grasslands and scrub, prairies, pinyon-juniper, ponderosa woodlands.
ELEVATION: 2,300–6,500 feet.
RANGE: AZ, CA, CO, NM, NV, UT, TX.
SIMILAR SPECIES: About 22 species of Senecio in NM, 2 others have hairless, thread-like leaves. Broom Groundsel, S. sparticoides, has ±5 rays with 0–3 tiny bractlets beneath the phyllaries. Riddell’s Groundsel, S. riddellii, is hairless and usually has 13 phyllaries and 8 rays. See key below.
NM COUNTIES: Statewide in low- to mid-elevation, arid habitats.
KEY to 3 species with thread-like leaves
1. Woolly-hairy leaves, bractlets beneath phyllaries minute or absent ... S. flaccidus var. flaccidus
+ Leaves hairless or nearly so ... (2)
2. Conspicuous bractlets 1/4 to 1/2 or more the length of the phyllaries, phyllaries 13 or 21, tips green or black … S. falccidus var. monoensis
+ tiny or no bractlets under phyllaries ... (3)
3. Tiny bractlets, less that 1/3 length of phyllaries, phyllaries mostly 13, tips green, rays 8 … S. riddellii
+ Bractlets absent or inconspicuous, phyllaries mostly 8, tips green … S. sparticoides
THREADLEAF GROUNDSEL (RAGWORT)
SENECIO FLACCIDUS
Aster Family, Asteraceae
Perennial herb
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Stems and leaves of the common Senecio flaccidus var. flaccidus are covered with white-woolly hairs.
The hairless Senecio flaccidus var. monoensis has ±21 phyllaries. Bractlets (arrow) are 1/2 the length of the phyllaries or longer.
The woolly-hairy Senecio flaccidus var. flaccidus has no or only minute bractlets (lower arrow) below the ±13 phyllaries. Phyllaries often have minute black tips (upper arrow).
Leaves are divided into thread-like segments along the midrib.
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