Chamise

Chamise “forms a large part of the chaparral of our mountain slopes, and when not in bloom
gives to them much the aspect imparted to the Scottish Highlands by the heather”³⁹⁹

Chamise (or greasewood, Adenostoma fasciculatum) is the dominant species in chaparral, which in turn is the dominant vegetation in California. Like many chaparral species, chamise has small leathery leaves that resist water loss, making it drought tolerant, and an enlarged, woody area, a burl, underground; this stores water and energy and facilitates rapid resprouting after a wildfire.

Chamise has a tenuous relationship with humans. Some people fear it for its flammability. Others enjoy it for the soft olive texture it brings to our hillsides and for the creatures it shelters.

Description ^{4,5,11,26,27,59}

Chamise is a native evergreen shrub, usually less than 12 feet (4 m) tall and densely branched with small, stiff branches. Several stems arise from a wooden mass or burl just below the soil surface. Older trunks develop grayish peeling bark. Younger stems are often reddish and may be smooth or covered with short, fine hairs. As the plant ages, dead wood accumulates. The small, resinous, evergreen leaves are needle-like, less than 1/2 inch (1.3 cm) long, in clusters that alternate along the stems. Leaves are olive green, more-or-less obovate, straight or curved. Leaf tips are smoothly rounded to obtuse or acute, and they often end with a tiny, hard point. The foliage resembles that of rosemary (Rosmarinus officinalis) or California buckwheat (Eriogonum fasciculatum).

Tiny flowers are densely packed into elongated clusters along branch ends. Flowers are radially symmetrical, bisexual, less than 7/32 inches (0.5 cm) across; clusters may be up to 5 inches (12 cm) long. There are five triangular sepals and and five, occasionally four, rounded petals. There are usually 10 or 15 stamens in five groups extending beyond the petals; anthers and pollen are light yellow. The single pistil has a superior ovary with one style and a somewhat lobed stigma, tinged with orange. The main flower period is April into July.¹

The dried flower surrounds the developing fruit, persisting to maturity and tipping the stem ends with shades of bronze and brown. The fruit is an achene with one or two tiny seeds.

Classification ^2,11,27

Chamise (Adenostoma fasciculatum) is a dicot angiosperm, in the rose family, Rosaceae. This is a variable family.⁴⁴ Plants generally have bisexual flowers that are radially symmetrical with five petals and five to numerous, spirally arranged stamens.

The rose family includes many commercial plants including fruits such as plums, peaches, apples and strawberries, and ornamentals such as roses and pyracantha. There are nine species i in the Reserve;⁴⁸ the most frequently encountered is toyon (Heteromeles arbutifolia).

Chamise is one of two species within the genus Adenostoma^2,306 and the only one in the Reserve.⁴⁸ Three varieties of chamise are currently accepted, distinguished on the basis of plant height, and leaf size and shape. I have examined only a few individuals and they fell in the range of overlap between var. fasciculatum and var. obtusifolium.

Ecology

Chamise is the quintessential chaparral species. It dominates much of that vegetation type, where its numerous short branches interweave with those of neighboring plants forming the impenetrable thicket that chaparral is known for. It also has most of the characteristics that adapt chaparral species to lack of summer rain and to periodic fires.^27,174 The leaves are small, thick and waxy, slowing water loss. The root system is extensive;^5,38  the main roots have been excavated to 25 feet (8 m) depth before disappearing, and root radial extent is generally twice that of the crown. Thus, chamise has efficient uptake of rain water as well as access to subsurface water sources. Thus, chamise has efficient uptake of rain water as well as access to subsurface water sources

Chamise stems arise from a large, subsurface, woody mass – a burl – which is protected from fire by the surrounding soil. The burl contains tissues capable of generating new growth, providing rapid regeneration after a fire.⁵ Chamise also produces two types of seed; a few are capable of germination the following season, but many need heat or chemical cues from fire to sprout. These build up a seed bank below the soil surface, providing new plants after a fire. Curiously, chamise is the only chaparral shrub with both strategies.^5,36 Neither strategy however, assures fire survival, which depends upon season, fire intensity and time since last burn.⁵

Ironically, chamise also has characteristics that seem to promote fire, such as small, resinous leaves that are highly flammable during the dry season (hence the common name greasewood),²⁶ and quantities of small, dead branches and dried flowers that accumulate in the canopy providing ready fuel.⁴²⁶ These would seem to be undesirable characteristics if burning is disadvantageous to chamise. The unanswered question is the extent to which these may be considered adaptations to promote fires, at least fires of the proper frequency and intensity to maximize the survival of chamise. The possibility that flammability is an ecological and evolutionary driving mechanism (like flower color and shape or drought tolerance) is currently receiving attention from ecologists.⁴²⁶

Human Uses

Native Americans used chamise medicinally, often as a wash for various ailments.²⁸² They used the hard wood as firewood, for construction and for tools.²⁸² To make flutes, the Chumash hollowed out the pithy core of small branches of elderberry (Sambucus nigra) with a drill or awl of chamise.¹⁵ Chumash, Luisaño and Kumeyaay made arrow foreshafts or arrow points from chamise. For foreshafts, green wood was dried in a groove of heated soapstone which straightened and hardened the wood. Kumeyaay made arrow points by heating chamise points carefully over coals until they got “hard as iron”.²⁷²

Interesting Facts

The name chamise comes from the Latin word “chamiso” and the Portuguese or Galican word “chamica,” meaning dry brush or firewood.^23,27 Thickets of chamise are sometimes called chamissal.⁴¹

The vegetation type, chaparral, is named after a similar scrubby dense vegetation type in Spain, “chaparro.”^36,41 Our word chaps – the thick leathery leg protectors that horsemen wear – comes from the same Spanish root.