''Hesperevax sparsiflora'' is a species of flowering plant in the family
Asteraceae known by the common name erect dwarf cudweed. It is native to
California and
Oregon, where it grows in several habitat types including sandy coastal areas and the
serpentine soil
Serpentine soil is an uncommon soil type produced by weathered ultramafic rock such as peridotite and its metamorphic derivatives such as serpentinite. More precisely, serpentine soil contains minerals of the serpentine subgroup, especially anti ...
s of inland hills. This is a small woolly annual herb reaching maximum heights under 18 centimeters. It has oval to rounded or scoop-shaped leaves on short
petioles which vary in morphology across varieties. Small
flower heads
A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...
appear between the leaves. They contain greenish or whitish disc florets.These florets are remarkably small, each being only 1/120th of an inch (0.2 millimeter) in width, and numbering 5 to 9 in the whole disc, which totals only 1/ 6th inch (3.8 mm) in width including bracts.
This is the world's smallest composite inflorescence.
There are two varieties:
*''Hesperevax sparsiflora.'' var. ''brevifolia'' (short-leaved evax) is an uncommon coastal variety with leaves generally under a centimeter long
*''Hesperevax sparsiflora'' var. ''sparsiflora'' is a longer-leaved variety which is more common but limited to California
References
External links
Calflora: ''Hesperevax sparsiflora'' (Erect dwarf cudweed, Erect evax, Few flowered evax)Jepson Manual eFlora (TJM2) treatmentUSDA Plants Profile for ''Hesperevax sparsiflora'' (erect dwarf-cudweed)UC CalPhotos: ''Hesperevax sparsiflora'' var. ''brevifolia''UC CalPhotos: ''Hesperevax sparsiflora'' var. ''sparsiflora''
Gnaphalieae
Flora of California
Flora of Oregon
Endemic flora of the United States
Natural history of the California chaparral and woodlands
Natural history of the California Coast Ranges
Taxa named by Asa Gray
Taxa named by Edward Lee Greene
Flora without expected TNC conservation status
{{Gnaphalieae-stub