Picrothamnus
Asteraceae tribe Anthemideae
bud sagebrush, budsage
1–10+, usually erect, diffusely branched from bases and throughout (some laterals persistent, forming thorns), villous to arachnose (hairs medifixed).
mostly cauline; alternate;
petiolate or sessile;
blades ± orbiculate to flabellate, simple or 1–2-pedately lobed (lobes orbiculate to spatulate or linear), ultimate margins entire, faces ± villous and gland-dotted.
usually cauline, sometimes mostly basal; alternate [opposite]; usually petiolate, sometimes sessile;
margins usually 1–3-palmately or -pinnately lobed (ultimate segments usually linear to filiform), sometimes not lobed, margins dentate or entire.
± obconic, 2–3(–5) mm diam.
convex (glabrous), epaleate.
flat to columnar or conic, epaleate or paleate (sometimes partially paleate; paleae usually falling, oblong to linear or filiform, flat or ± conduplicate).
0 (peripheral pistillate florets 2–8; corollas pale yellow, ± filiform, ± villous).
0 or in 1(–2+) series, usually pistillate and fertile, rarely neuter or styliferous and sterile;
corollas usually yellow or white, sometimes reddish to cyanic (sometimes combinations within corollas).
0 or (in disciform heads) in 1–3+ series;
corollas usually present, usually yellow, sometimes ochroleucous or reddish to cyanic (sometimes combinations within corollas), sometimes lacking.
5–13(–15), functionally staminate;
corollas pale yellow (± villous), tubes ± cylindric, throats campanulate, lobes 5, ± deltate.
persistent, 5–8 in ± 2 series, distinct, ± obovate, subequal, margins and apices (hyaline) narrowly scarious.
persistent or falling, usually in 3–5+ series, distinct, unequal, and wholly scarious or with margins and/or apices notably scarious, sometimes in 1–2 series, distinct, subequal, and herbaceous with margins and/or apices barely scarious.
0.
disciform, usually (2–12+) in ± leafy, racemiform to spiciform arrays, rarely borne singly.
homogamous (discoid) or heterogamous (radiate or disciform), usually in corymbiform, paniculiform, racemiform, or spiciform arrays, sometimes borne singly or in subcapitate clusters.
(brown) obovoid to ellipsoid, ribs 0, faces ± villous and obscurely nerved (pericarps without myxogenic cells or resin sacs);
pappi 0.
monomorphic or dimorphic within heads, usually obovoid or columnar to prismatic, sometimes 3-angled or -winged, or compressed or obcompressed (then often winged);
pappi usually 0 (cypselar wall tissues sometimes produced as pappus-like, entire or lobed to toothed wings, coronas, or tubes), if present, pappi persistent or falling, usually of scales, rarely of bristles.
(inner) florets usually bisexual and fertile, rarely functionally staminate;
corollas usually yellow, sometimes ochroleucous or reddish to cyanic (sometimes combinations within corollas);
anther bases obtuse, not tailed, apical appendages ± ovate;
styles abaxially glabrous or papillate (distally), branches linear, adaxially stigmatic in 2 lines from bases to apices, apices ± truncate, appendages rings of papillae or essentially 0.
= 9.
Picrothamnus
Asteraceae tribe Anthemideae
Species 1.
Separation of Picrothamnus from Artemisia calls attention to differing views of generic circumscription within Anthemideae (see discussion under Artemisia). Distinguished by its spinescent branches and relatively large heads held among the leaves, Picrothamnus is among the more distinct of proposed segregates. The diffuse-porous woods (S. Carlquist 1966) correspond to the early spring-blooming phenology of the plants and provide an anatomic feature that helps to distinguish Picrothamnus from Artemisia.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 100+, species 1700+ (26 genera, 99 species in the flora).
Centers of concentration for anthemids are in the Mediterranean regions of Europe and Africa, in central Asia, and in southern Africa.
Studies by L. E. Watson et al. (2000) and syntheses by K. Bremer and C. J. Humphries (1993) and by C. Oberprieler et al. (unpubl.) have resulted in changes in circumscriptions for some genera and in better understandings of relationships among genera of anthemids.
From 1753 until near the end of the 20th century, the mums and florists’ chrysanthemums of horticulture, along with marguerites, Paris daisies, Shasta daisies, and others, were included by most botanists in Chrysanthemum. Then, traditional Chrysanthemum came to be dismembered (see, e.g., K. Bremer and C. J. Humphries 1993) and the mums, florists’ chrysanthemums, and their closest relatives came to be treated botanically in the genus Dendranthema. A great hue and cry ensued from horticulturalists, especially in Europe. The upshot was that a proposal to typify Chrysanthemum on C. indicum (florists’ chrysanthemum) succeeded, and that generic name is once again applied to the mums and florists’ chrysanthemums of horticulture, none of which is known to be well established in the flora area. Here, the marguerites and Paris daisies are treated in Argyranthemum, Shasta daisies in Leucanthemum, and corn chrysanthemums and crown daisies in Glebionis.
Some cultivated members of Anthemideae have been reported as ephemeral or ± persistent escapes in the flora area. Some of those are documented in generic treatments below; others include florists’ chrysanthemum (Chrysanthemum indicum, which may be encountered as abandoned plantings almost anywhere in the flora area) and Shasta daisy (reported for Michigan as Chrysanthemum ×superbum J. K. Ingram by E. G. Voss 1972–1996, vol. 3; see treatment of Leucanthemum).
Centipeda minima (Linnaeus) A. Braun & Ascherson has been recorded from Massachusetts and Pennsylvania as non-persistent introductions. The plants are somewhat succulent, gland-dotted annuals with stems decumbent to procumbent, leaves oblanceolate to cuneate, mostly 5–15 mm, usually lobed or toothed distally, heads disciform, involucres hemispheric or broader (2–3+ mm diam.), phyllaries in 2–4 series, pistillate florets in 2–8 series, bisexual florets 10(–30), corollas yellow, 4-lobed, and cypselae obovoid, 1–1.5 mm, epappose. Traditionally, Centipeda has been included in Anthemideae; in more recent studies, it has been placed in Astereae (e.g., E. V. Boyko 2003; G. L. Nesom 2000) or in Centipedinae within Athroismeae (J. L. Panero 2005).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Heads discoid or disciform (ray florets 0; if peripheral florets pistillate, lacking corollas or corollas lacking laminae) | → 2 |
1. Heads radiate (ray florets 3–35+, corollas with laminae) | → 14 |
2. Heads disciform (peripheral florets pistillate, disc florets bisexual or functionally staminate) | → 3 |
2. Heads discoid (all florets bisexual, fertile) | → 8 |
3. Pistillate corollas lacking | → 4 |
3. Pistillate corollas ± tubular (distally 3–5-lobed or truncate) | → 5 |
4. Pistillate corollas lacking; disc florets 12–200+, bisexual and fertile (heads pedunculate) | Cotula |
4. Pistillate corollas lacking (styles sheathed by pericarp tissues, soon indurate, becoming spinelike); disc florets 2–8+, functionally staminate (heads sessile). | Soliva |
5. Heads usually in lax to dense, corymbiform arrays, rarely borne singly; involucres mostly hemispheric or broader, (3–)5–22+ mm diam.; phyllaries (20–)30–60+ in (2–)3–5+ series | Tanacetum |
5. Heads usually in paniculiform, racemiform, or spiciform arrays, sometimes in subcapitate clusters, sometimes borne singly; involucres hemispheric to campanulate, obconic, ovoid, or turbinate, 1.5–5(–12) mm diam.; phyllaries 5–20+ in 1–4(–7) series | → 6 |
6. Heads borne singly or (2–20+) in usually corymbiform, rarely paniculiform, arrays or in subcapitate clusters; disc floret corollas bright yellow or ochroleucous (leaves usually gland-dotted) | Sphaeromeria |
6. Heads (usually 20–200+, 2–12+ in Picrothamnus) in paniculiform, racemiform, or spiciform arrays, rarely borne singly; disc floret corollas usually pale yellow, rarely red | → 7 |
7. Subshrubs or shrubs (thorny); disc florets functionally staminate (corollas ± villous) | Picrothamnus |
7. Annuals, perennials, subshrubs, or shrubs (not thorny); disc florets bisexual and fertile or functionally staminate (corollas usually glabrous, sometimes hairy, not villous) | Artemisia |
8. Subshrubs or shrubs | → 9 |
8. Annuals or perennials | → 11 |
9. Leaf blades usually 1-pinnately lobed (lobes usually crowded, not in one plane, overall effect ± vermiform); receptacles paleate; disc florets 60–250+ | Santolina |
9. Leaf blades not lobed or 1–2+ pinnately and/or palmately lobed, sometimes apically 3-lobed or -toothed (not vermiform); receptacles epaleate (except Artemisia palmeri); disc florets 3–20(–30+) or 40–100+ | → 10 |
10. Heads borne singly or in loose, corymbiform arrays; phyllaries 22–40 in 3–4+ series; disc florets 40–100+; cypselae narrowly obovoid to oblong or elliptic, ± terete or flattened, ribs 5; pappi of 1 (often cupped or earlike) or 3–5 (erose to lacerate) scales | Pentzia |
10. Heads in paniculiform, racemiform, or spiciform arrays; phyllaries 12–20+ in 4–7 series; disc florets 2–20(–30+); cypselae columnar, obovoid, or fusiform, ribs 0 (and faces finely striate) or 2–5; pappi usually 0 (coroniform in A. californica and A. papposa) | Artemisia |
11. Perennials | → 12 |
11. Annuals (scarious tips of inner phyllaries not notably dilated; receptacles conic or oblong-ovoid to ± hemispheric or globose) | → 13 |
12. Receptacles convex, epaleate; disc corolla tubes ± cylindric (proximally swollen, becoming spongy in fruit, not clasping apices of cypselae) | Leucanthemum |
12. Receptacles hemispheric to conic, paleate; disc corolla tubes ± cylindric (bases saccate, weakly clasping apices of cypselae) | Chamaemelum |
13. Phyllaries lance-triangular to ± ovate or elliptic (carinate); cypselae columnar to prismatic, ribs 4 (pericarps without myxogenic cells); pappi coroniform (shorter adaxially) | Oncosiphon |
13. Phyllaries oblong or ovate to spatulate or linear-spatulate (not carinate); cypselae obconic, slightly compressed, ribs 5 (pericarps sometimes with myxogenic cells); pappi 0, coroniform, or adaxial auricles | Matricaria |
14. Receptacles wholly or partially paleate | → 15 |
14. Receptacles epaleate | → 19 |
15. Heads in compact to open (± flat-topped), corymbiform or compound-corymbiform arrays; ray florets 3–5(–12); disc florets (5–)15–30+ (cypselae obcompressed) | Achillea |
15. Heads borne singly or in lax, corymbiform arrays; ray florets 5–30+; disc florets 40–300+ (cypselae mostly not, sometimes weakly, obcompressed) | → 16 |
16. Disc corolla tubes ± cylindric (bases ± saccate or spurred, ± clasping apices of ovaries and/or cypselae); cypselae: ribs or nerves (weak): 2 lateral, 1 adaxial | → 17 |
16. Disc corolla tubes ± compressed or cylindric (bases sometimes proximally dilated, not saccate or spurred); cypselae: ribs 9–10, or 0, or 2 lateral (sometimes ± winged) plus 3–10 finer ribs on each face | → 18 |
17. Phyllaries 16–24 in 2–3+ series; ray corollas orange, yellow, or white with yellow bases | Cladanthus |
17. Phyllaries 22–45+ in 3–4+ series; ray corollas white | Chamaemelum |
18. Perennials; ray corollas yellow | Cota |
18. Annuals (biennials); ray corollas usually white, rarely yellow or pink. | Anthemis |
19. Cypselae dimorphic: outer (ray) usually 3-angled and ± winged (except Mauranthemum); inner (disc) ± compressed-prismatic or ± flattened (angles winged), or ± quadrate (1 or 2 angles sometimes winged), or columnar (not winged) | → 20 |
19. Cypselae ± monomorphic, outer and inner similar (0 notably winged) | → 24 |
20. Subshrubs or shrubs | Argyranthemum |
20. Annuals | → 21 |
21. Stems and leaves hirtellous to pilosulous (some hairs gland-tipped, plants sticky, viscid) | Heteranthemis |
21. Stems and leaves glabrous or hairy (hairs not gland-tipped, plants not viscid) | → 22 |
22. Ray corollas proximally white or red to purple, distally yellow or white; disc corollas proximally ochroleucous, distally red to purple (phyllaries ± carinate) | Ismelia |
22. Ray corollas mostly white (usually yellowish at bases) or mostly yellow (sometimes paler distally); disc corollas ± yellow (phyllaries not carinate) | → 23 |
23. Involucres 8–12(–15+) mm diam.; ray floret corollas white (usually yellowish at bases, drying pinkish), laminae oblong to ovate (6–12+ mm); disc corolla lobes (2–)5 (without resin sacs) | Mauranthemum |
23. Involucres 15–25+ mm diam.; ray floret corollas mostly yellow, sometimes paler distally, laminae linear, oblong, or ovate (8–25 mm); disc corolla lobes 5 (each with a resin sac) | Glebionis |
24. Shrubs (leaves mostly clustered distally on stems; pappi crowns of scales) | Nipponanthemum |
24. Annuals, biennials, perennials | → 25 |
25. Annuals | → 26 |
25. Biennials or perennials | → 28 |
26. Leaves usually irregularly 1-pinnately lobed or toothed; involucres ± hemispheric, 8–12(–15+) mm diam; disc florets 60–100+; cypselae: ribs 7–10 | Mauranthemum |
26. Leaves (1–)2–3-pinnately lobed; involucres 4–14 mm diam.; disc florets 120–750+; cypselae: ribs 3–5 | → 27 |
27. Cypselae obconic, slightly compressed (usually asymmetric, apices oblique), ribs 5, faces smooth between ribs (pericarps without resin sacs, or resin sacs within lateral ribs) | Matricaria |
27. Cypselae trigonous, ± compressed, ribs 3–5 (0–2 abaxial, 2 lateral, 1 adaxial, usually whitish, relatively thick, smooth), faces smooth or rugose to tuberculate between ribs (pericarps usually with 2–3, sometimes 1–5, mostly abaxial-apical, resin sacs) | Tripleurospermum |
28. Heads usually in lax to dense, corymbiform arrays, rarely borne singly; pappi usually coroniform, rarely 0 | Tanacetum |
28. Heads usually borne singly or in 2s or 3s, sometimes in corymbiform arrays; pappi usually 0, sometimes crowns of 6–12 irregular teeth | → 29 |
29. Ray florets styliferous and sterile | Leucanthemella |
29. Ray florets pistillate and fertile | → 30 |
30. Cypselae trigonous, ± compressed, ribs 3–5 (0–2 abaxial, 2 lateral, 1 adaxial, usually whitish, relatively thick, smooth), faces smooth or rugose to tuberculate between ribs (pericarps usually with 2–3, sometimes 1–5, mostly abaxial-apical, resin sacs) | Tripleurospermum |
30. Cypselae ± columnar, cylindro-obconic, obconic, or obovoid, ribs 5–10 (pericarps without apical resin sacs) | → 31 |
31. Plants (10–)50–130(–200+) cm; disc corolla tubes ± cylindric (proximally swollen, becoming spongy in fruit); cypselae ± columnar to obovoid, ribs ± 10 (pericarps with myxogenic cells) | Leucanthemum |
31. Plants mostly (0.6–)5–40+ cm; disc corolla tubes ± cylindric (not swollen, not becoming spongy in fruit); cypselae ± obconic to cylindro-obconic, ribs 5 or 5–8(–10) (pericarps without myxogenic cells) | → 32 |
32. Leaves not lobed, margins entire; involucres (4–)4.5–6(–6.5) mm diam.; phyllaries 20–26(+) in 2(–3+) series (receptacles ± villous) | Hulteniella |
32. Leaves usually pinnati-palmately lobed (lobes 3–7), ultimate margins coarsely crenate, dentate, or entire; involucres 13–29 mm diam. (flattened); phyllaries (22–)25–34(–44) in 3(–4) series (receptacles glabrous) | Arctanthemum |
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