"God has an inordinate fondness for stars and beetles, for he made so many of them."
- J.B.S. Haldane
Asteraceae is one of the most diverse families in California and the world, with literally hundreds of species. Almost 200 pages of the Jepson Manual are dedicated to describing the California species alone. There are a great number of well known plants in this family.
Asteraceae was formerly known as Compositae because this family is distinguished by the compound nature of the flowers. These plants are still commonly referred to as the composites. The disks of the flowerheads are actually composed of many small flowers packed together. The 'petals' are created by the ray flowers around the perimeter of the disk. The flowers are usually very showy, designed to attract pollinators. Many species produce large numbers of short lived seeds.
The growth forms of Asteraceae range from annuals to trees, but in California, they are almost exclusively annuals and herbaceous perennials. There are some important shrubs as well, but the species diversity clearly goes to the smaller plants. With the exception of Baccharis, the shrubs are herbaceous or barely woody, with thin, brittle stems.
Members of Asteraceae are fast growing, relatively short lived and often amenable to horticulture or site disturbance. Many species have found their way into agriculture and gardening. A disturbing number are weeds.
Asteraceae
(Compositae)
Dicot Plant Families
Plant Relationships |
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Native Genera: |
Achillea |
(Yarrow) |
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Other Common Genera: |
Anthemis |
(Chamomile) |
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Related Families: |
Campanulaceae |
(in APG System (Jepson 2012)) |
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Description |
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Growth Forms: |
Most are annuals and herbaceous perennials. Some are shrubs. The shrubs have thin branches that are either herbeceous or barely woody. There are trees in the Asteraceae, but none in California. |
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Branching: |
Alternate. |
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Leaves: |
Usually simple, but some are indented or even highly dissected (eg. - Artemisia, Tanacetum). |
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Flowers: |
What appear to be flowers are actually collections of tiny flowers stacked side by side. The flowers in the middle are called 'disk flowers' and usually have very small petals. The flowers around the edge are called 'ray flowers'. They often have enlarged outside petals that serve as petals for the entire flower cluster. |
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Seed and Fruit: |
Asteraceae are designed to produce large numbers of seeds. The seeds often have hairs on them to make them disperse in the wind. The seeds are usually small and short lived. |
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Growing Conditions |
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Sun and Exposure: |
Most members of Asteraceae grow in full sun. |
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Soil and Moisture Requirements: |
Asteraceae are found in all soil and moisture conditions. They tend toward early successional sites or in areas that remain open and sunny, often with harsh or poor growing conditions. As a result, Asteraceae are common in dry grasslands, meadows, deserts, seabluffs, fresh erosion and disturbed soil. The thrive in disturbed and cultivated ground. Although they survive in poor soil, they take full advantage of fertility (nitrogen) when it is present. The propensity for open, difficult and disturbed sites, combined with the small, easily dispersed seed, makes Asteraceae preadapted for weediness. Some of the most significant weeds (thistle, dandelion, ox-tongue, goundsel, cocklebur, et. al.) are Asteraceae. |
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Horticulture and Restoration |
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Horticultural Comments: |
Many members of Asteraceae are widely used in landscaping. They are usually fast growing plants found in full sun. They range from drought tolerant to moisture loving. Most will either tolerate or respond well to irrigation. They benefit from rich, well drained soil. |
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Wildlife Habitat: |
A few shrubs will provide shelter, but most Asteraceae benefit wildlife with their flowers, which provide pollen and nectar to the pollinators. |
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Restoration Projects: |
The most commonly used Asteraceae shrubs in northern and central California are Baccharis pilularis and Artemisia californica. Baccharis is one of the most adaptable and successful shrubs, but it doesn't get much respect because it is very common and not particularly showy. Artemisia (sagebrush) is fragrant and prettier, but is more restricted in potential sites. Annual and herbaceous perennial members of Asteraceae are used in restoration projects for species diversity. They generally don't comprise the foundation of a restoration, although they represent a higher proportion of the community on seabluffs and near tidal marshes. |
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California Native
Plant Guide
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