Calycadenia truncata

{{Short description|Species of flowering plant}}

{{Speciesbox

| image = Oregon western rosinweed imported from iNaturalist photo 17609 on 23 September 2024.jpg

| genus = Calycadenia

| species = truncata

| authority = DC.

| synonyms_ref = [http://www.theplantlist.org/tpl1.1/record/gcc-120684 The Plant List, Calycadenia truncata DC.]

| synonyms =

• Calycadenia scabrella Greene
• Calycadenia truncata var. scabrella (Drew) Jeps.
• Calycadenia truncata subsp. scabrella (Drew) D.D.Keck
• Hemizonia scabrella Drew
• Hemizonia truncata (DC.) A.Gray
• Lagophylla scabrella M.E.Jones

}}

Calycadenia truncata is a species of flowering plant in the family Asteraceae known by the common name Oregon western rosinweed. It is native to western North America.

Calycadenia truncata is an annual herb producing an erect, reddish stem, reaching up to {{convert|120|cm|in|abbr=off}} in height.{{Cite book |last=Spellenberg |first=Richard |url=https://archive.org/details/nationalaudubons00spel/page/361/ |title=National Audubon Society Field Guide to North American Wildflowers: Western Region |publisher=Knopf |year=2001 |isbn=978-0-375-40233-3 |edition=rev |pages=361-362 |orig-date=1979}} The leaves are linear (long and very narrow) and up to {{convert|10|cm|in|abbr=on|frac=4}} long. Blooming from June to October, the inflorescence bears one or more flower heads about {{Convert|2.5|cm|abbr=on|frac=4}} at separate nodes, surrounded by short bracts tipped with resin glands. The hairy flower heads have a center of many purple-tipped disc florets as well a few yellow ray florets {{Convert|6-13|mm|frac=4}} in length. The fruit is an achene.[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=220002197 Flora of North America, Calycadenia truncata de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 695. 1836. ]

It is native to southwestern Oregon and northern and central California. It is found in the Cascades, the Coast Ranges, and the foothills of the Sierra Nevada as far south as Monterey and Tulare Counties.[http://bonap.net/MapGallery/County/Calycadenia%20truncata.png Biota of North America Program 2014 county distribution map][http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=1328 Calflora taxon report, University of California, Calycadenia truncata DC., rosin weed ] It thrives on dry and sunny grassy slopes.