Machaeranthera

Nees

Gen. Sp. Aster., 13, 224. 1832.

Etymology: Latin machaera, sword, and anthera, anther, alluding to curved, sword-shaped anther appendages
Treatment appears in FNA Volume 20. Treatment on page 394. Mentioned on page 12, 383, 385, 386, 395, 402, 403, 406.
 TaxonIllustrator 
FNA20 P42 Xanthisma coloradoense.jpegXanthisma coloradoense
Machaeranthera tanacetifolia
Dieteria bigelovii var. bigelovii
Dieteria canescens var. canescens
Yevonn Wilson-Ramsey
Bee F. Gunn
Bee F. Gunn
Bee F. Gunn

Annuals or biennials, 5–100 cm; taprooted. Stems erect, much branched (when well developed), moderately to densely hairy, usually stipitate-glandular. Leaves basal (usually withering) and cauline; sessile; blades lanceolate to elliptic, pinnatifid, 2-pinnatifid, deeply lobed, or dissected (lobes aristate), ultimate margins entire, faces moderately to densely hairy, stipitate-glandular. Heads radiate, borne singly (on leafy peduncles 5–30 mm). Involucres broadly turbinate to hemispheric, (5–11 ×) 10–18 mm. Phyllaries 24–80 (–100) in 3–6 series, appressed, spreading, or reflexed, 1-nerved (flat to keeled), lanceolate to linear, unequal, bases ± indurate, apices herbaceous, margins not scarious, faces proximally glabrous, distally moderately to densely hairy, stipitate-glandular. Receptacles flat to convex, pitted, epaleate. Ray-florets 8–40 (–50), pistillate, fertile; corollas blue, violet, or purple. Disc-florets 14–160, bisexual, fertile; corollas yellow, tubes shorter than funnelform throats, lobes 5, erect, deltate to lanceolate; style-branch appendages lanceolate. Cypselae narrowly to broadly obovoid, slightly compressed, 8–18-ribbed, faces sparsely to densely hairy (hairs antrorse or appressed); pappi persistent, of 30–80 white to tawny, barbellate, apically attenuate bristles in 1–3 series. x = 4.

Distribution

w North America, n Mexico

Discussion

Species 2 (2 in the flora).

The relationships of Machaeranthera have long been unclear, and much disagreement has occurred about its circumscription. It has been included in Aster by some and maintained as a separate genus by others. In addition, all or parts of many other genera have been included in Machaeranthera by various authors, such as Xylorhiza, Dieteria, Arida, Xanthisma, Psilactis, and Rayjacksonia. Studies of chloroplast DNA and nuclear ribosomal DNA, in combination with chemical and cytological studies, do not support previous circumscriptions of Machaeranthera (D. R. Morgan and B. B. Simpson 1992; Morgan 1997, 2002). Those studies suggest that none of the other taxa are closest relatives of Machaeranthera, and they were treated as separate genera by Morgan and R. L. Hartman (2003).

Selected References

None.

Key

1 Involucres hemispheric; phyllary apices spreading to reflexed; disc corolla lobes 0.3–0.7 mm, glabrous or glabrate Machaeranthera tanacetifolia
1 Involucres broadly turbinate; phyllary apices appressed; disc corolla lobes 0.7–1 mm, hairy Machaeranthera tagetina

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... more about "Machaeranthera"
not tailed +, rounded +  and obtuse +
distinct +
subequal +
scarious +
usually triangular +  and linear +
usually deltate +  and lanceolate +
spiciform +, racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
David R. Morgan +  and Ronald L. Hartman +
decurrent +
indurate +
compound +  and simple +
lanceolate;elliptic pinnatifid 2-pinnatifid deeply lobed or dissected +
rugulose +  and muricate +
white +  and tawny +
not 2-lipped +  and actinomorphic +
yellow +, purple +, violet +  and blue +
compressed +  and obovoid +
fertile +  and bisexual +
fertile +  and bisexual +
w North America +  and n Mexico +
Latin machaera, sword, and anthera, anther, alluding to curved, sword-shaped anther appendages +
hairy +, stipitate-glandular +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
broadly turbinate;hemispheric +
cauline +  and basal +
deltate +  and lanceolate +
dentate to pinnatifid +  and entire +
not scarious +
2-carpellate +
persistent +
reflexed +, spreading +  and appressed +
lanceolate +  and linear +
Gen. Sp. Aster., +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
exalbuminous +
stipitate-glandular +  and hairy +
appendaged +  and truncate +
papillate +  and smooth +
Compositae +
Machaeranthera +
Asteraceae tribe Astereae +
biennial +  and annual +
5 cm50 mm <br />0.05 m <br /> (100 cm1,000 mm <br />1 m <br />) +
tree +, shrub +  and subshrub +