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Desert Dandelion - Malacothrix torreyi

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Species of Concern

Global Rank: G4
State Rank: S1S2
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM: SENSITIVE
MNPS Threat Rank: 3

External Links






State Rank Reason (see State Rank above)
Desert dandelion is limited in Montana to a few localized sites on the south side of the Pryor Mountains. Impacts of grazing are unknown, but it may respond positively to moderate levels of disturbance. Additional data on population levels and trends are needed.
  • Details on Status Ranking and Review
    Desert Dandelion (Malacothrix torreyi) Conservation Status Review
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General Description
Desert Dandelion is a taprooted annual with milky sap and a basal rosette of leaves giving rise to one to several erect or ascending stems that are 1-3 dm high. The basal leaves are up to 10 cm long, have petioles, and are deeply pinnately divided into toothed and pointed lobes. The few stem leaves are reduced upwardly. The foliage has sparse long hair when young but is glabrous with age, other than the sparse, glandular hairs in the inflorescence. The several stalked flower heads arise from reduced upper leaves, or bracts, in an open inflorescence. Flower heads nod in the bud but become erect in flower. Each is 8-13 mm high with 2 series of involucral bracts, the outer of which is very short, and the inner of which is long-pointed. Rays are yellow and ca. 1 cm long, and disk flowers are lacking. The cylindrical achenes are 5-ribbed, 3-4 mm long, and topped by a pappus of numerous unbranched, white bristles that are united at the base and fall as one when seeds mature.

Phenology
Flowering takes place in June.

Diagnostic Characteristics
Several genera have yellow dandelion-like flower heads on leafy stems. Species of Hieracium differ in that they are perennial and have leaves with entire or shallowly lobed margins. The genus Lactuca has involucral bracts in more than two series and Sonchus has clasping stem leaves. Species of Crepis are perennial or have shallowly lobed leaves.

Species Occurrences
Number of Species Occurrences: 6
*Not all Species Occurrences are mapped

 


Range Comments
WY, eastcentral ID, and southcentral MT to southeast OR, south to AZ, NV, and possibly CA. Disjunct.

Summary of Observations Submitted for Montana
Number of Observations: 8

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Relative Density

Recency

 

(Records associated with a range of dates are excluded from time charts)



Habitat
Desert dandelion occurs locally below 1525 m (5000 feet) on the south side of the Pryor Mountains (Lesica and Achuff 1992). Information from the few known occurrences suggests that it prefers sandy alluvium, often occurring with Artemisia tridentata, Atriplex gardneri, Astragalus geyeri and Bouteloua gracilis.


Ecology
This species is an annual, suggesting that population sizes may vary greatly between years. The low stature and annual habit also suggest that it may suffer from competition with larger plants, may require sparse vegetation and could respond positively to moderate levels of disturbance (Lesica and Achuff 1992).

Management
Populations are subject to grazing, but the effects are unknown. Grazing removes the palatable, more competitive grasses and may favor species like M. torreyi. However, many species in the Tribe Lactuceae are palatable to ungulates.

References
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
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    • Davis, W. S. 1986. Reproductive biology of MALACOTHRIX (Asteraceae). American Journal of Botany. 73:758-759.
    • Lesica, P. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX.
    • Lesica, P. and P. L. Achuff. 1992. Distribution of vascular plant species of special concern and limited distribution in the Pryor Mountain desert, Carbon County, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, MT. 105 pp.
    • Tomb, A. S., D. A. Larson, and J. J. Skvarla. Pollen morphology and detailed structure of Family COMPOSITAE, Tribe CICHORIEAE. I. Subtribe STEPHANOMERIINAE. American Journal of Botany. 61(5):486-498.
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Citation for data on this website:
Desert Dandelion — Malacothrix torreyi.  Montana Field Guide.  Montana Natural Heritage Program.  Retrieved on November 28, 2014, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=PDAST660L0
 
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