Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Hemizonia

hayfield tarweed, tarweed
Habit Annuals, 5–80 cm.
Stems

± erect.
Leaves

mostly cauline;

proximal opposite (forming winter–spring rosettes, sometimes present at flowering), mostly alternate;

sessile;

blades narrowly elliptic to linear or lance-linear, margins serrulate or entire, faces puberulent, hispidulous, hirsute, strigose, sericeous, or villous (distal leaves sometimes stipitate-glandular as well).
Involucres

hemispheric to ± urceolate or globose, 3–8+ mm diam. (usually subtended by calyculi of 5–7 bractlets in H. congesta subsp. calyculata).
Receptacles

flat to conic, glabrous, paleate (paleae connate, forming cells around all or most individual disc florets, scarious, ± deliquescent).
Ray florets

5–14, pistillate, fertile;

corollas white or yellow (often purple-veined abaxially).
Disc florets

5–60+, functionally staminate;

corollas white or yellow, tubes shorter than funnelform throats, lobes 5, deltate (anthers ± dark purple; styles glabrous proximal to branches).
Phyllaries

5–14 in 1 series (linear to lanceolate or oblanceolate, herbaceous, each usually 1/2 enveloping a subtended ray floret proximally, abaxially pubescent to hirsute or villous, and stipitate-glandular).
Heads

radiate, borne singly or in ± paniculiform, racemiform, or spiciform arrays or in glomerules.
Disc cypselae

0;

pappi 0.
Ray cypselae

± obcompressed, abaxially gibbous, basal attachments oblique, apices sometimes beaked, beaks inconspicuous, straight, diameters greater than lengths, faces glabrous;

pappi 0.
Peduncular

bracts: pit-glands, tack-glands, and/or spines 0.
x

= 14.

Hemizonia
Distribution
from USDA
w North America
[BONAP county map]
Discussion

Species 1.

Hemizonia as often circumscribed (to include Centromadia and Deinandra) is polyphyletic; molecular phylogenetic studies have indicated that Centromadia and Deinandra are more closely related to Calycadenia, Holocarpha, and Osmadenia than to Hemizonia in the strict sense, which is most closely related to Blepharizonia, also with 2n = 28 (S. Carlquist et al. 2003). Crosses between taxa of Hemizonia have yielded hybrids of minimal to full fertility; natural hybrids also have been documented (J. Clausen 1951). All taxa in Hemizonia are self-incompatible. The name H. congesta subsp. congesta has been sometimes misapplied to plants treated here as H. congesta subsp. lutescens; the type of H. congesta corresponds to plants that have been called H. leucocephala, a synonym of H. congesta subsp. congesta (B. G. Baldwin et al. 2001).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 21, p. 291. Authors: Bruce G. Baldwin, John L. Strother.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Madiinae
Subordinate taxa
H. congesta
Name authority de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 692. (1836)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America, OregonFlora

The species comparison tool is brought to you by:
Northwest Wildflowers