Picrothamnus

Nuttall

Trans. Amer. Philos Soc., n. s. 7: 417. 1841.

Common names: Budsage
Etymology: Greek picro- , bitter, and thamnos, bush, alluding to bitterness of the plants
Treatment appears in FNA Volume 19. Treatment on page 498. Mentioned on page 52, 53, 486.
 TaxonIllustrator 
FNA19 P57 Chamaemelum nobile.jpegChamaemelum nobile
Santolina chamaecyparissus
Picrothamnus desertorum
Yevonn Wilson-Ramsey
Yevonn Wilson-Ramsey
John Myers

Subshrubs or shrubs, 5–30 (–50) cm (strongly aromatic). Stems 1–10+, usually erect, diffusely branched from bases and throughout (some laterals persistent, forming thorns), villous to arachnose (hairs medifixed). Leaves 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. Heads disciform, usually (2–12+) in ± leafy, racemiform to spiciform arrays, rarely borne singly. Involucres ± obconic, 2–3 (–5) mm diam. Phyllaries persistent, 5–8 in ± 2 series, distinct, ± obovate, subequal, margins and apices (hyaline) narrowly scarious. Receptacles convex (glabrous), epaleate. Ray-florets 0 (peripheral pistillate florets 2–8; corollas pale-yellow, ± filiform, ± villous). Disc-florets 5–13 (–15), functionally staminate; corollas pale-yellow (± villous), tubes ± cylindric, throats campanulate, lobes 5, ± deltate. Cypselae (brown) obovoid to ellipsoid, ribs 0, faces ± villous and obscurely nerved (pericarps without myxogenic cells or resin sacs); pappi 0. x = 9.

Distribution

w North America

Discussion

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.

Selected References

None.

... more about "Picrothamnus"
not tailed +  and obtuse +
scarious +
racemiform +  and spiciform +
indeterminate +  and determinate +
Leila M. Shultz +
Nuttall +
decurrent +
lobed;less orbiculate;flabellate +
Budsage +
zygomorphic +, actinomorphic +  and (3-)5-merous +
winged +  and monomorphic +
obovoid +  and ellipsoid +
fertile +  and bisexual +
w North America +
Greek picro- , bitter, and thamnos, bush, alluding to bitterness of the plants +
gland-dotted +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
sessile +  and petiolate +
deltate +
entire +  and dentate +
2-carpellate +
persistent +
Trans. Amer. Philos Soc., n. s. +
styliferous +, neuter +  and pistillate +
sterile +  and fertile +
bearing subulate enations +, hairy +  and bristly +
exalbuminous +
villous +  and arachnose +
1 +  and 10 +
appendaged +  and truncate +
papillate +
Compositae +
Picrothamnus +
Asteraceae tribe Anthemideae +
campanulate +
cylindric +
perennial +, biennial +  and annual +
30 cm300 mm <br />0.3 m <br /> (50 cm500 mm <br />0.5 m <br />) +
shrub +  and subshrub +