Brickellia sect. Leptanthodium Robinson (1917: 24)

Schilling, Edward E., Scott, Randall W. & Panero, Jose L., 2015, A revised infrageneric classification for Brickellia (Asteraceae, Eupatorieae), Phytotaxa 234 (2), pp. 151-158 : 155-156

6. Brickellia sect. Leptanthodium Robinson (1917: 24) . Lectotype (here chosen):— Brickellia diffusa A. Gray.

Species:— Brickellia diffusa A. Gray ; B. filipes B.L. Rob. ; B. coulteri A. Gray ; B. glabrata B.L. Rob.

Geographic distribution:—Mostly Baja California and Pacific coastal Mexico. Elevation range is 0–2000 m ( B. filipes 0–600 m, B. diffusa 0–2000 m, B. coulteri 0–1600 m, B. glabrata 0–300 m, Baja S).

Phenology:—Most of these taxa flower Oct–Jan (Apr, B. glabrata ) except for B. coulteri var. brachiata ; see below.

Habitat:—Often tropical deciduous, but desert washes and hillsides ( B. coulteri ).

Endemism:—Only B. glabrata is regionally endemic (to southern Baja California Sur, Mexico); others are widespread, and B. diffusa has become a pantropical weed.

Morphological trends:—Plants are annuals, herbaceous perennials, or subshrubs. The leaves are often truncate and hastately toothed at base ( B. coulteri and B. glabrata ), and the leaves are long petiolate (2–3.5 cm), all taxa have erect heads and flowers generally few per head (8–12; 20 in B. glabrata ).

Taxonomic issues:—The section includes two somewhat disparate pairs of species that have never been grouped previously, but there is some morphological support to go with the molecular phylogenetic results showing them to form a clade ( Schilling et al. 2015). Brickellia coulteri var. brachiata (A. Gray) B.L. Turner is an allopatric taxon found in the desert washes of northeastern Sonora and San Luis Potosi (700–2000 m) and flowers in all seasons ; it might represent a distinct species.

7. Brickellia sect. Microphyllae (B.L.Rob.) E.E. Schill. & R. Scott , stat. nov. Brickellia sect. Bulbostylis subsect. Microphyllae Robinson (1917: 40) . Type (Art. 22.6):— B. microphylla A. Gray.

Species:— Brickellia arguta B.L. Rob. ; B. atractyloides A. Gray ; B. frutescens A. Gray ; B. glutinosa A. Gray ; B. greenei A. Gray ; B. incana A. Gray ; B. laccata Flyr ; B. microphylla A. Gray ; B. nevinii* A. Gray ; B. oblongifolia Nutt. ; B. veronicifolia (Kunth) A. Gray ; B. vollmeri * Wiggins.

Geographic distribution:—Sierra Madre Oriental-Central Plateau—southwestern US ( B. greenei , northern California — Oregon; B. oblongifolia , north to Canada). Generally found at lower elevations (100–800 m up to 1500 m) but a few range up to 2400 m ( B. microphylla , B. veronicifolia , B. greenei ).

Phenology:—Varied, B. fructescens and B. atractyloides (spring: Mar/Apr–Jun); B. oblongifolia (May–Aug), B. microphylla and B. greenei (Jul–Oct.); B. laccata (northern Coahuila endemic) Sep–Nov whereas its sister taxon, B. glutinosa with which it overlaps in distribution (southeastern Chihuahua — Coahuila), habitat (limestone cliffs), and elevation range, flowers Jun–Sep. The widespread B. veronicifolia flowers Mar.–Jan. Trends: year-round flowering ( B. veronicifolia ); summer (Jun–Sep): B. oblongifolia , B. microphylla , B. greenei , B. glutinosa (correlates with northern distribution except for B. glutinosa ); Spring (Mar/Apr–June): B. atractyloides , B. fructescens ).

Habitat:—Xeric canyon walls, limestone cliffs, dry granitic slopes, arroyos. Brickellia oblongifolia is found in (oftentimes cold) desert grasslands.

Endemism:—Five more or less widespread species ( B. veronicifolia , B. oblongifolia , B. microphylla , B. atractyloides , B. fructescens ) and three narrow endemics ( B. greenei , B. laccata , B. glutinosa ).

Morphological trends:—Shrubs (except B. greenei , herbaceous perennial), leaves sessile or short petiolate, glandular, usually numerous flowers per head, heads erect, pedunculate, corollas funnelform, cypselae with 4–6 ribs.

8. Brickellia sect. Phanerostylis (A. Gray) E.E. Schill. & R. Scott , stat. nov. Eupatorium subgen. Phanerostylis Gray (1882: 205) . Phanerostylis (A. Gray) King & Robinson (1972: 70). Brickellia subgen. Phanerostylis (A. Gray) Turner (1978: 343) . Type:— Eupatorium coahuilense A. Gray (= Brickellia coahuilensis [A.Gray] Harc. & Beaman).

Species:— Brickellia coahuilensis (A. Gray) Harc. & Beaman ; B. hintoniorum B.L. Turner ; B. nesomii B.L. Turner ; B. pedunculosa (DC.) Harc. & Beaman ; B. problematica B.L. Turner.

Geographic distribution:—Central Plateau (Coahuila, Nuevo Leon, Tamaulipas, San Luis Potosi, Puebla); B. problematica is disjunct in Oaxaca. Primarily at high elevation: ca. 2000–3000 m ( B. coahuilensis , B. hintoniorum , B. pedunculosa ), 3000–3700 m ( B. nesomii ), 1800–2400 m ( B. problematica ).

Phenology:—Primarily summer–fall (Jul–Oct); Sep–Feb ( B. pedunculosa ).

Habitat:—Mostly dry to mesic pine-oak woodlands.

Endemism:—All species are more or less widespread and locally abundant where they occur, thus are regional endemics.

Morphological trends:—Mostly perennial herbs ( B. problematica is annual), cypselae 1–2(–5) ribbed; corolla lobes are ampliate.