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Havard's false willow

chaparral broom, coyote brush, dwarf chaparral false willow

Habit Subshrubs, 15–70 cm (much branched from bases). Shrubs, 15–450 cm (prostrate and mat-forming to erect and rounded, much branched).
Stems

erect (green to tan), slender, striate-angled, glabrous, resinous.

spreading to ascending, dark brown, shiny, striate-angular, glabrous, often ± scurfy, usually resinous and sticky.

Leaves

present at flowering; short-petiolate;

blades (1-nerved) narrowly spatulate to linear, 20–40 × 2–3 mm, reduced to bracts distally, bases attenuate, margins entire or toothed (teeth to 2 mm), faces glabrous, gland-dotted, resinous.

present at flowering;

sessile or short-petiolate;

blades (1- or 3-nerved) oblanceolate to obovate, the smaller 5–40 × 2–15 mm (thick), bases cuneate, margins entire or coarsely dentate (teeth 3–9 distal to middles), faces glabrous, gland-dotted, resinous.

Involucres

cylindro-campanulate;

staminate 3 mm, pistillate 4–4.5 mm.

hemispheric to campanulate;

staminate 3.2–5 mm, pistillate 3–6 mm.

Pistillate florets

15–20;

corollas 3 mm.

19–43;

corollas 2.5–3.5 mm.

Staminate florets

12–15;

corollas 3–4 mm.

20–34, 3–4 mm.

Phyllaries

lanceolate, 1–4 mm, margins scarious, medians green or brownish, apices obtuse to acuminate (thickened, slightly erose and ciliate).

ovate to lanceolate, 1–3 mm, margins yellowish, scarious, medians yellow proximally, green distally, apices obtuse to acute or acuminate (erose, abaxial faces papillose-scurfy).

Heads

in broad paniculiform arrays.

(100–200+) in (leafy) paniculiform arrays.

Cypselae

2–2.5 mm, 5-nerved, glabrous;

pappi 4 mm.

1–2 mm, 8–10-nerved, glabrous;

pappi 6–9 mm.

Baccharis havardii

Baccharis pilularis

Phenology Flowering Jul–Sep.
Habitat Dry rocky hillsides, open ground, calcareous gravels
Elevation 1500–2300 m (4900–7500 ft)
Distribution
from FNA
NM; TX; Mexico (Chihuahua)
[BONAP county map]
from FNA
CA; NM; OR; nw Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Found mainly in the Chisos and Davis Mountains of West Texas, Baccharis havardii is distinguished by its short bushy habit, narrow leaves with elongate teeth, and 5-nerved cypselae. G. L. Nesom (pers. comm.) suggested that it is weakly defined and further investigation may demonstrate it should be included in the Mexican species B. sulcata de Candolle (which name would have priority over B. havardii).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Subspecies 2 (2 in the flora).

Baccharis pilularis can be distinguished by its dark brown stems, and serrate, obovate to oblanceolate leaves. In addition, plants from some dunes of the California coast are prostrate, a growth form unique to this genus in our region.

The common, weedy, widespread form is subsp. consanguinea, which is typically erect, with its larger leaves 15–40 mm. Subspecies pilularis is known only from exposed sandy dunes and bluffs along the central coast of California. Its growth habit is matlike, and its larger leaves are 5–15 mm. The prostrate habit of subsp. pilularis is strikingly different from the upright habit of subsp. consanguinea.

C. B. Wolf (1935) demonstrated that in at least some populations, the distinction between prostrate and erect forms has a genetic basis. Transplants from the wild of the prostrate and erect forms retained their respective growth habits when grown together in a sheltered location and the morphology of seedlings reflected the habit of the parents. Wolf’s arguments for recognizing the forms as subspecies are further supported by the existence of prostrate cultivars in the horticultural trade. On the other hand, both erect and prostrate forms grow in proximity throughout the range of subsp. pilularis. In many areas the forms intergrade completely; in others they can be easily distinguished. Two subspecies are recognized here, notwithstanding difficulties in identifying habit from pressed specimens, or by observations of populations where both growth forms coexist. Further study is needed, perhaps utilizing molecular characters and detailed observations of native populations.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Stems erect, rarely prostrate, brittle, forming erect or rounded shrubs; leaves mostly 15–40 mm; noncoastal and coastal California, Oregon
subsp. consanguinea
1. Stems prostrate, flexible, forming mats; leaves mostly 5–15 mm; sandy, exposed habitats of coastal California
subsp. pilularis
Source FNA vol. 20, p. 28. FNA vol. 20, p. 29.
Parent taxa Asteraceae > tribe Astereae > Baccharis Asteraceae > tribe Astereae > Baccharis
Sibling taxa
B. angustifolia, B. bigelovii, B. brachyphylla, B. dioica, B. glomeruliflora, B. glutinosa, B. halimifolia, B. malibuensis, B. neglecta, B. pilularis, B. plummerae, B. pteronioides, B. salicifolia, B. salicina, B. sarothroides, B. sergiloides, B. texana, B. thesioides, B. vanessae, B. wrightii
B. angustifolia, B. bigelovii, B. brachyphylla, B. dioica, B. glomeruliflora, B. glutinosa, B. halimifolia, B. havardii, B. malibuensis, B. neglecta, B. plummerae, B. pteronioides, B. salicifolia, B. salicina, B. sarothroides, B. sergiloides, B. texana, B. thesioides, B. vanessae, B. wrightii
Subordinate taxa
B. pilularis subsp. consanguinea, B. pilularis subsp. pilularis
Name authority A. Gray: in A. Gray et al., Syn. Fl. N. Amer. 1(2): 224. (1884) de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 407. (1836)
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