White-stem Blazing Star
Mentzelia albicaulis
This Whitestem Blazing Star was observed in Rainbow Valley, Maricopa Co., Arizona, USA on 9 April 2010.
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ANNUAL: Spring annual appearing in years after good winter rains.
Generally low growing and considerably less than ½
meter tall.
FLOWERS: Bright yellow flowers with five petals, many stames; petals
12 mm long. Blooming mid to late spring depending on available moisture.
LEAVES: Green leaves are variously lobed and supported on stems that are
conspicuously whitened.
RANGE: Middle and upper elevations of the Sonoran Desert, often in
transition to chaparral or desert grassland habitats. In washes and on bajadas.
Ranges through mush of wesrtn North America.
FRUIT: The seed pods, roughly 25 mm in length, develop below the
flower and are slightly enlarged towards the tip. Numerous small seeds. Mentzelia
desertorum is very similar to M. albicaulis but apparently
separable by the seeds which are smooth vs. roughened and by the number of
chromosomes in the cells - these characters require a microscope making
identification in the field uncertain.
UNARMED: No spines or thorns.