Silphium perplexum

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Distribution Map: Based on vouchered plant specimens only. View county names by placing the mouse cursor over a particular county.

Family:	ASTERACEAE
Species:	Silphium perplexum J.R. Allison
Common Name:	Old Cahaba Rosinweed
Habitat:	Glades and prairies.
Associated Ecological Communities:	**
Growth Habit:	Herb
Duration:	Perennial
Category:	Vascular
USDA Symbol:	**
Plant Notes:	Old Cahaba Rosinweed is a native herbaceous perennial in the Aster family (Asteraceae). It is an Alabama endemic, known from three counties in west central Alabama. All known populations are located within nine miles of the Cahaba River. Old Cahaba Rosinweed is a perennial from a short rhizome. Basal leaves are usually absent at flowering. The stems are from one to eight feet in height, and are unbranched below the inflorescence. Stem leaves are lanceolate or ovate, opposite, and sessile or with short winged petioles. The leaf bases clasp the stem. The leaf margins may be entire or with a few teeth. The stems, leaves, and phyllaries are pubescent and glandular. The glands are stalked and amber colored. The entire plant has a resinous feel. Flowers are produced in heads. The heads are arranged in open panicles. Each plant may have from one to thirty heads. Ray and disc flowers are bright yellow. Rays average 19-23 per head. The fruit is an achene. Old Cahaba Rosinweed is similar to another Alabama endemic-- Sticky Rosinweed (Silphium glutinosum J.R. Allison). That species is known only from Bibb County. It is a shorter plant with fewer ray flowers and longer stalked glands. Old Cahaba Rosinweed is postulated to have arisen from hybridization between Sticky Rosinweed and Entire Leaf Rosinweed (Silphium integrifolium Michaux) as it is intermediate in most characteristics between those two species. Old Cahaba Rosinweed is listed as an S1 species in Alabama (typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream, or some factor of its biology making it especially vulnerable in the state), and globally as a G1 species (critically imperiled globally because of extreme rarity (5 or fewer occurrences), or very few remaining acres, or miles of stream) or especially vulnerable to extinction because of some factor of its biology).--A. Diamond
Taxonomic Notes:	**
Status:	Native, Endemic, S1 (State Rank), G1 (Global Rank)
References:	**
Specimen:	View specimen details in the Alabama Herbarium Consortium Specimen Database

** Not applicable or data not available.

Classification

Family	ASTERACEAE - Aster family
Genus	Silphium
Species	Silphium perplexum J.R. Allison - Old Cahaba Rosinweed

Citation

Citation	Silphium perplexum J.R. Allison, Castanea 66(1–2): 188–189, f. 12D–F. 2001.
Basionym:	**
Type:	USA: ALABAMA: Dallas Co.: ca. 15.5 km SW of Selma and ca. 2.4 km WSW of Old Cahaba; S side Co. Rd. 2 at jct. Co. Rd. 9; prairielike openings over chalk, 18 Aug 1999, James R. Allison 12153 (holotype, GH; isotypes: AUA, DUKE, FLAS, FSU, GA, JSU, MICH, MO, NY, UNA, US, VDB).

** Not applicable or data not available.

Synonyms

No synonyms exist for this species.

No synonyms exist for this species.

Specimens and Distribution

This species has been reported in the following counties by the herbaria listed. An overview of the individual specimens are provided in the table that follows. Click on the accession number to view details; click on column headers to sort; choose a county or herbaria to filter the specimen data.

Counties included on distribution map: Dallas, Perry

Herbaria represented by specimen data listed below: ALNHS, AMAL, AUA, NY, TROY, UNA, UWAL

Range of years during which specimens were collected: -

Barcode / Accession No.	County	Coll. Date	Collector & Collection No.	Herbarium & Herbarium Name Used
UWAL0016545	Dallas	13 Aug 2014	Diamond, Alvin R. 25441	UWAL Silphium perplexum J.R. Allison
AUA000007343	Perry	21 Aug 1994	ALLISON, JAMES R. 8564	AUA SILPHIUM PERPLEXUM J. ALLISON
NY00688600	Dallas	18 Aug 1999	James R. Allison 12153	NY Silphium perplexum J.R.Allison
UNA00060060	Dallas	18 Aug 1999	Allison, James R. 12153	UNA Silphium perplexum J. Allison
UWAL0018008	Perry	29 Jul 1972	Kral, Robert 47891	UWAL Silphium perplexum J. Allison
TROY000041585	Dallas	13 Aug 2014	Diamond, Alvin R. 25440	TROY Silphium perplexum J.R. Allison
AMAL00021285	Dallas	21 Jul 2010	Barger, T. Wayne 444	AMAL Silphium perplexum J. Allison
AUA000007389	Dallas	18 Dec 1999	ALLISON, JAMES R. 12155	AUA SILPHIUM PERPLEXUM J. ALLISON
AMAL00003395	Perry	08 Oct 2000	Allison, James R. 12583	AMAL Silphium perplexum J. Allison
ALNHS00005210	Dallas	20 Sep 2017	Barger, T. Wayne SP#3424	ALNHS Silphium perplexum J. Allison
UNA00060052	Perry	19 Aug 1999	Allison, James R. 12160	UNA Silphium perplexum J. Allison
AUA000007341	Perry	21 Aug 1994	ALLISON, JAMES R. 8564	AUA SILPHIUM PERPLEXUM J. ALLISON
AMAL00003393	Dallas	18 Aug 1999	Allison, James R. 12155	AMAL Silphium perplexum J. Allison
UWAL0030308	Dallas	24 Jul 2015	Keener, Brian R. 9043	UWAL Silphium perplexum J.Allison
UNA00060014	Perry	08 Oct 2000	Allison, James R. 12583	UNA Silphium perplexum J. Allison
UWAL0016544	Dallas	13 Aug 2014	Diamond, Alvin R. 25440	UWAL Silphium perplexum J.R. Allison
AUA000030967	Dallas	18 Aug 1999	ALLISON, JAMES R. 12153	AUA SILPHIUM PERPLEXUM J. ALLISON
AUA000007344	Perry	21 Aug 1994	ALLISON, JAMES R. 8564	AUA SILPHIUM PERPLEXUM J. ALLISON
UNA00060050	Dallas	18 Aug 1999	Allison, James R. 12155	UNA Silphium perplexum J. Allison
UWAL0018009	Perry	29 Jul 1972	Kral, Robert 47891	UWAL Silphium perplexum J. Allison
UWAL0030304	Dallas	24 Jul 2015	Keener, Brian R. 9036	UWAL Silphium perplexum J.Allison
AUA000007390	Dallas	18 Aug 1999	ALLISON, JAMES R. 12155	AUA SILPHIUM PERPLEXUM J. ALLISON
AUA000007393	Perry	8 Oct 2000	ALLISON, JAMES R. 12583	AUA SILPHIUM PERPLEXUM J. ALLISON
UWAL0018010	Perry	29 Jul 1972	Kral, Robert 47891	UWAL Silphium perplexum J. Allison
UNA00060051	Dallas	18 Aug 1999	Allison, James R. 12155	UNA Silphium perplexum J. Allison
TROY000041595	Dallas	13 Aug 2014	Diamond, Alvin R. 25441	TROY Silphium perplexum J.R. Allison
AUA000007391	Perry	19 Aug 1999	ALLISON, JAMES R. 12161	AUA SILPHIUM PERPLEXUM J. ALLISON
AMAL00003394	Dallas	18 Aug 1999	Allison, James R. 12153	AMAL Silphium perplexum J. Allison
ALNHS00002273	Dallas	21 Jul 2010	Barger, T. Wayne OC-444	ALNHS Silphium perplexum J. Allison
UNA00055852	Perry	_ _ 1995	Allison, James R. 8119	UNA Silphium perplexum J. Allison
UNA00060053	Perry	19 Aug 1999	Allison, James R. 12161	UNA Silphium perplexum J. Allison
AUA000007342	Perry	21 Aug 1994	ALLISON, JAMES R. 8564	AUA SILPHIUM PERPLEXUM J. ALLISON
AMAL00003391	Perry	19 Aug 1999	Allison, James R. 12161	AMAL Silphium perplexum J. Allison
NY00688599	Dallas	18 Aug 1999	James R. Allison 12153	NY Silphium perplexum J.R.Allison
UNA00060015	Perry	08 Oct 2000	Allison, James R. 12583	UNA Silphium perplexum J. Allison
UWAL0018007	Dallas	06 Oct 1972	Kral, Robert 48820	UWAL Silphium perplexum J. Allison
AUA000007392	Perry	19 Aug 2001	ALLISON, JAMES R. 12161	AUA SILPHIUM PERPLEXUM J. ALLISON
AMAL00003392	Dallas	18 Aug 1999	Allison, James R. 12155	AMAL Silphium perplexum J. Allison
UNA00057718	Perry	_ _ 1995	Allison, James R. 8119	UNA Silphium perplexum J. Allison
UNA00060054	Perry	19 Aug 1999	Allison, James R. 12161	UNA Silphium perplexum J. Allison
TROY000048284	Dallas	17 Sep 2019	Diamond, Alvin R. 29092	TROY Silphium perplexum J.R. Allison

View a List of All Ecological Communities

For more information, contact: Brian R. Keener, Ph.D.

Data last modified: 8/1/2025

Web Development: The Florida Center for Community Design + Research

A member of the University of South Florida family of PlantAtlas.org sites

Citation Information:

Keener, B.R., A.R. Diamond, T.W. Barger, L.J. Davenport, P.G. Davison, S.L. Ginzbarg, C.J. Hansen, D.D. Spaulding, J.K. Triplett, and M. Woods. 2025. Alabama Plant Atlas. [S.M. Landry and K.N. Campbell (original application development), Florida Center for Community Design and Research. University of South Florida]. University of West Alabama, Livingston, Alabama.

Data, text, and images licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License.

Silphium perplexum

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Classification

Citation

Synonyms

Specimens and Distribution