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lemonscent, low pectis, Mexican chinchweed

Habit Annuals, 2–15 cm; herbage spicy-scented (lemon-scented in some Mexican populations). Annuals, perennials, subshrubs, or shrubs, (1–)5–50(–120+)[200+] cm.
Leaves

10–40 mm, bases of distal blades not notably expanded.

mostly cauline, sometimes basal or basal and cauline; mostly opposite (distal sometimes alternate) or mostly alternate;

petiolate or sessile;

blades usually elliptic, filiform, lanceolate, linear, or ovate, often 1(–2)-pinnately lobed, ultimate margins entire or toothed (often proximally bristly-ciliate), faces glabrous or puberulent to tomentose (usually bearing oil-glands, embedded pellucid glands filled with strong-scented, essential oils).

Peduncles

5–15 mm.

Involucres

campanulate, cylindric, hemispheric, obconic, or turbinate.

Receptacles

flat or convex to hemispheric or conic, epaleate (receptacles sometimes pitted, pit margins sometimes fimbrillate to laciniate).

Ray florets

0 or 1–21+, pistillate, fertile;

corollas yellow to orange (sometimes with brown or mostly brown) or white to pink, magenta, or reddish purple.

Disc florets

1–120+, usually bisexual and fertile [functionally staminate];

corollas yellow to orange or brown, or pinkish to purplish or reddish, tubes much shorter than to much longer than cylindric to funnelform throats, lobes 5, deltate to lance-linear (equal or unequal);

anther thecae pale or ± darkened;

stigmatic papillae in 2 lines.

Phyllaries

linear, 3–5 mm, widest near middles, each with 1 subterminal oil-gland 0.2–0.5 mm plus smaller, submarginal oil-glands.

falling or persistent, 3–21+ in 1–2 series (distinct or ± connate, mostly linear to lanceolate, usually subequal, usually some or all bearing pellucid oil-glands as in leaves).

Calyculi

0 or of 1–22 bractlets.

Heads

radiate or discoid (sometimes radiant, e.g., in Thymophylla), usually borne singly, sometimes in loose to crowded, corymbiform or cymiform arrays.

Cypselae

2.5–4 mm;

pappi of 0–7 awns or bristles 1–3 mm and/or coroniform.

mostly clavate to obpyramidal (lengths usually 2–3+ times diams.), glabrous or hairy;

pappi usually persistent, of 20–50 bristles in 1–2+ series, or of 5–20 (sometimes aristate) scales in 1–2 series, or combinations of bristles and scales in 1–2+ series, rarely coroniform or 0.

2n

= 24.

Pectis angustifolia var. tenella

Asteraceae tribe Heliantheae subtribe Pectidinae

Phenology Flowering Jun–Dec.
Habitat Deserts, grasslands, arid woodlands, shrublands, roadsides
Elevation 100–1100(–2500) m (300–3600(–8200) ft)
Distribution
from FNA
NM; TX; Mexico (Aguascalientes, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, Veracruz, Zacatecas)
[BONAP county map]
Mostly subtropical; tropical; and warm-temperate; especially arid New World
Discussion

Variety tenella is widely distributed in the Chihuahuan Desert and adjacent regions. The isolated occurrence in northern New Mexico perhaps represents an introduction.

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

Genera 22, species 225 (9 genera, 38 species in the flora).

Circumscription of Pectidinae has been fairly constant for decades. The group is sometimes given tribal rank, as Tageteae. Here, we have followed H. Robinson (1981). The group is usually distinguished on the basis of schizogenous glands containing essential oils (mostly terpenes) in tissues of leaves and/or phyllaries (sometimes in tissues of other organs as well).

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

Key
1. Leaves opposite (blade margins proximally bristly-ciliate; ray florets borne on bases ofsubtending phyllaries; style branches of bisexual florets knoblike)
Pectis
1. Leaves opposite or mostly alternate (blades often lobed, margins sometimes bristly-ciliate; ray florets borne on receptacles, not on bases of subtending phyllaries; style branches of bisexual florets linear)
→ 2
2. Phyllaries distinct to bases or nearly so
→ 3
2. Phyllaries ± connate 1/3–7/8+ their lengths (margins of outer may be free to bases)
→ 6
3. Calyculi of (0–)1–9, deltate, lanceolate, or linear bractlets; pappi wholly or partly of scales (individual scales sometimes comprising 5–10, basally connate bristles)
→ 4
3. Calyculi 0; pappi wholly of distinct bristles
→ 5
4. Ray corollas yellow to orange
Dyssodia
4. Ray corollas whitish with pinkish or purplish stripes
Nicolletia
5. Heads radiate
Chrysactinia
5. Heads discoid
Porophyllum
6. Calyculi 0; pappi of 2–5(–10) elements in ± 1 series (usually 0–5+ oblong to lanceolate, erose-truncate to laciniate, plus 0–2+ longer, subulate or aristate, some or all sometimes connate)
Tagetes
6. Calyculi usually of (1–)5–8(–22) bractlets, rarely 0; pappi usually of 8–20 elements in 2 series, rarely coroniform
→ 7
7. Bractlets of calyculi subulate or pectinate
Dysodiopsis
7. Bractlets of calyculi (deltate to subulate) not pectinate
→ 8
8. Plants (20–)30–70+ cm; involucres (7–18 ×) 5–12 mm; phyllaries weakly connate 1/3–2/3 their lengths
Adenophyllum
8. Plants mostly (1–)5–30 cm; involucres (4–6 ×) 2–7 mm; phyllaries strongly connate 2/3–7/8 their lengths (margins of outer may be free to bases)
Thymophylla
Source FNA vol. 21, p. 229. FNA vol. 21, p. 221.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Pectidinae > Pectis > Pectis angustifolia Asteraceae > tribe Heliantheae
Sibling taxa
P. angustifolia var. angustifolia, P. angustifolia var. fastigiata
Subordinate taxa
Adenophyllum, Chrysactinia, Dysodiopsis, Dyssodia, Nicolletia, Pectis, Porophyllum, Tagetes, Thymophylla
Synonyms P. tenella subtribe Tageteae
Name authority (de Candolle) D. J. Keil: Rhodora 79: 58. (1977) Lessing: Linnaea 5: 134. (1830)
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