TARWEED
    Blooming in July and on, tarweed mascaras the horses' muzzles and provides that wonderul fragrance typical of California summertime.

Here's some information from a classic guidebook:

"Under the common designation of "tarweed," plants belonging to two different genera-- Madia and Hemizonia-- and comprising thirty or forty species, may be found. They are mostly annuals or biennials, with viscid, heavily-scented foliage, which makes them conspicuous in the late summer through the autumn.

    The hemizonias are distinctively Californian; while the madias we have in common with Chile. Their viscid exudation is particularly ruinous to wool and clothing, but alcohol is a solvent for it, and will generally remove it.
    We wonder how these plants, which flourish in our driest seasons, can extract so much moisture from the parched earth, and of what practical use this resinous secretion can be in their economy.

    Though some of them are described as having a disagreeable odor, many of them have a very pleasant balsamic fragrance, which gives our summer and autumn atmosphere a peculiar character of its own. Whole fields and hillsides are tinged with their warm olive foliage, or are yellow with their golden flowers, which appear like a fall revival of the buttercups. The flowers open mostly at night or in early morning, closing in bright sunshine."
    The Wildflowers of California, by Mary Elizabeth Parsons, illustrated by Margaret Warriner Buck, first published in 1897. Copyright California Academy of Sciences.