Overview

Brief Summary

Introduction

Hecastocleidoideae contains one genus and one species.

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Comprehensive Description

Biology

Very little is known about the biology of Hecastocleis; no pollinators were seen during visits to the Red Pass/Tidus Canyon populations.  Since the florets and bracts are whitish perhaps they attract night time visitors.
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Historical Overview and Morphology

Hecastocleis shockleyi A. Gray was described in 1882 and its unusual morphology and restricted distribution has made it sought after for herbarium specimens.  This shrub is easily identified because of its single flowered heads that are re-aggregated on a receptacle in groups of 1-5 heads; each group of heads is subtended by a relatively large spiny whitish or greenish bract (Figures 1-5).  Gray (1882) commented that is was "a remarkable addition to the few known North American Mutisieae, to stand near Ainsliaea but altogether sui generis and of peculiar habit."  According to Williams (1977) the generic name Hecastocleis, "…comes from the Greek roots, ekastos meaning 'each' and kleio meaning 'to shut up", referring to each flower having its own involucre.  The species was named after William H. Shockley one of the first botanical collectors from Nevada (Barneby, 1977).  Bremer (1994) placed the genus in the tribe Mutisieae subtribe Mutisiinae, and Hind (2006) placed it in the Mutisieae in a group by itself. 

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Pollen

The pollen of Hecastocleis is psilate and tricolpate (see Figure 11, Chapter 10; Telleri & Katinas 2005).  Based on his examination of the pollen and the literature Wodehouse (1929) stated that “Hecastocleis is a monotypic genus with no close connections in the tribe, but is regarded as closest to Ainsliaea; its pollen grains are rather dissimilar to any in the tribe, but show greatest similarity to those of Ainsliaea”.  The phylogeny, based on DNA, indicates that Hecastocleis is separated from Ainsliaea by the intervening Carduoideae.  It is bracketed by the African Mutisieae (Dicomeae, Oldenbergia, Tarchonantheae) plus the Cardueae on one side and the Gochnatieae on the other.  The pollen resembles that of the basal grade, especially the Gochnatieae.
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Chemistry

No information is available on the chemistry of Hecastocleis.
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Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

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Global Range: This plant occurs in western Nevada and into the deserts of California in Inyo, Mono, San Bernardino and Riverside counties.

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Biogeography

The distribution of Hecastocleis is confined to the southwestern USA.  It has been collected from the mountains surrounding Death Valley and on many of the isolated mountains around southern Nevada.  In fact, just about every local flora that is published from the southern Nevada/Death Valley area lists this species as occurring in its range, i.e., Charleston Mountains (Clokey 1951), Nevada Test Site (Beatley 1976), Grapevine Mountains (Kurzius 1981), and the flora of the Desert National Wildlife Range (Ackerman 2003).  In general it seems to be widespread in the southern Nevada and adjacent California area but growing in isolated populations.  The easiest place to see it is on the way to Death Valley, at Red Pass, the highest point on the dirt road from Beatty, Nevada to Leadfield and Titus Canyon, California.

Hecastocleis is an anomaly in the Area Cladogram for the Compositae (see supertree chapter 3).  Below the node where one finds this genus the branches are estimated to have a southern South American distribution.  Above Hecastocleis the more highly nested clades have radiations in Africa and Asia but most resolve to Africa, especially southern Africa.  So, the obvious question is, what happened in the past that has left this pattern where a plant from southern Nevada is on the cladogram between the basal South American grade and the African and Asian explosions?  There are several possible explanations.  Two equally likely based on the Area Cladogram: 1) there was a dispersal event from South America to North American and then one from North America to Africa, or 2) there was a dispersal event from South American to North America followed by radiation across North America and Europe and down into Africa and over to Asia followed by extinction of all but Hecastocleis.  Dispersal from South America to North America has happened in several of the groups in this part of the tree, for instance, Gochnatia hypoleuca (DC) A. Gray is a member of the Gochnatieae tribe which is found at the node below Hecastocleis.  There is, of course, a third possibility, that the placement of Hecastocleis is incorrect.  It is a rather long branch and there might be some ‘long branch attraction’ affecting the phylogeny.  However, bootstrap support for the separation of Hecastocleis from the Gochnatieae is strong (100%).

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Physical Description

Morphology

Description

Leaves: blades 1–4 cm, bases ± clasping, margins thickened, usually with 3–6 spines 1–3 mm near bases, apices mucronate or acute. Phyllaries usually lanate on margins. Corollas pinkish purple in bud, white at flowering, ca. 10 mm. Cypselae brown, 5 mm; pappi 1–2 mm. 2. = 16.
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Diagnostic Description

Formal Description

Subfamily Hecastocleoideae and Tribe Hecastocleideae Panero & Funk (2002)

(Keil 1993, Panero & Funk 2002, Simpson 2006, Hind 2006, & personal observations)

Subshrubs or shrubs to 40-80 (-150) cm.  Leaves alternate, cauline, sessile, blades linear to narrowly ovate with 3 main veins, stiff, margins entire, apex acute usually with a spine, base attenuate, margins with a few spines, surfaces glabrous or minutely tomentoseHeads single flowered, clustered in second-order heads, each cluster with 1-5 heads and subtended by ovate to orbiculate bracts with spiny margins.  Involucres (each enclosing 1 floret) cylindric to fusiform, 10 mm.  Receptacle flat, nude.  Florets 1, bisexual, fertile; corollas reddish purple to greenish white, actinomorphic, deeply 5-lobed; stamens 5, anther basal appendages slightly fimbriate, apical appendages lanceolate acute; style branches short, (0.1-0.5 mm), apices rounded.  Achene terete, not beaked, obscurely 4-5 nerved, glabrescent; pappus of 6 unequal, lanceolate or multi-toothed scales sometimes fused to form lacerate crowns. 

Hecastocleis is obviously a well-defined genus without close relatives and confined to high elevations (ca. 5000 ft) in southern Nevada and adjacent California.  It is easily recognizable from a distance by it relatively large whitish to greenish bracts that subtend the clusters of single flowered heads.

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Type Information

Isotype for Hecastocleis shockleyi A. Gray
Catalog Number: US 958294
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): W. Shockley
Locality: Candelaria., Esmeralda, Nevada, United States, North America
Elevation (m): 1829
  • Isotype: Gray, A. 1882. Proc. Amer. Acad. Arts. 17: 221.
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Isotype for Hecastocleis shockleyi A. Gray
Catalog Number: US 387882
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): W. Shockley
Locality: Candelaria., Esmeralda, Nevada, United States, North America
Elevation (m): 1829
  • Isotype: Gray, A. 1882. Proc. Amer. Acad. Arts. 17: 221.
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Ecology

Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 300

Comments: There are approx. 20-25 occurrences in California and more in Nevada. It is not actively tracked in either state. There is quite a bit of speculation that there are many more occurrences in the desert currently undocumented.

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Physiology and Cell Biology

Cell Biology

Chromosomal Data

The basic chromosome number is estimated to be x=8, based on one count (Powell et al. 1974).
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Hecastocleis shockleyi

The following is a representative barcode sequence, the centroid of all available sequences for this species.


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Statistics of barcoding coverage: Hecastocleis shockleyi

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N4 - Apparently Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Hecastocleis shockleyi is a regional endemic and known from Nevada and California. While it is restricted in its range it does appear to be relatively common. Some 20-25 occurrences are documented in California, but is expected that this species is under observed. Further, the habitat is generally inaccessible. It is believed that even older reports of this species in the Inyo and Mono Counties and western Nevada are probably still extant. The habitat this species occupies is also common so this supports the idea that it is under observed. This species tends to occur scattered where it is found and is not usually a dominant component of the vegetation (CNPS, CNDDB).

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Comments: Often found on carbonate or slate.

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Global Short Term Trend: Unknown

Global Long Term Trend: Unknown

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Threats

Degree of Threat: Low

Comments: There may be some threat of mining at some sites since this plant can occur on calcareous substrate.

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Management

Biological Research Needs: Need information on reproductive rate, life span, etc.

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Wikipedia

Hecastocleis

Hecastocleis is a genus of plants in the daisy family containing the single species Hecastocleis shockleyi.[1][2] It is known by the common name prickleleaf. This plant is native to the desert mountains and plains of eastern California (Inyo, Mono, Kern, + San Bernardino Counties) and southern Nevada (Mineral, Esmeralda, Nye, Lincoln, + Clark Counties), where it grows on arid, rocky slopes and flats.[3][4][5]

Description[edit]

This is a low, brambly shrub producing a tangle of stiff, branching stems reaching heights between 40 and 70 centimeters. The stems have sparse glandular hairs and are lined with small pointed green leaves with a row of widely spaced spines along each edge. As the leaf dries and its flesh falls away, the spines remain as hard prickles.[4]

At the end of stem branches are solitary flower heads, each enclosed between flat, oval-shaped, sharply toothed, leaflike, pale yellow bracts. Between the bracts are the flower parts, which are pinkish when new and open into a greenish-yellow corolla. The fruit is a cylindrical achene.[4]

Classification[edit]

Hecastocleis shockleyi is the only species in the subfamily Hecastocleidoideae of the aster family (Asteraceae). Botanists at least as early as Asa Gray (in 1882) remarked on its distinctiveness; it appears to have no close relatives within the aster family.[6][7]

References[edit]

  1. ^ Gray, Asa. 1882. Proceedings of the American Academy of Arts and Sciences 17: 220–221 description in Latin, commentary in English
  2. ^ Tropicos, Hecastocleis A. Gray
  3. ^ Biota of North America Program 2013 county distribution map
  4. ^ a b c Flora of North America, Vol. 19, 20 and 21 Page 71, Hecastocleis A. Gray
  5. ^ Calflora, Hecastocleis shockleyi A. Gray, Shockley's prickleleaf, prickleleaf
  6. ^ Panero, JL; VA Funk (2002-12-30). "Toward a phylogenetic subfamilial classification for the Compositae (Asteraceae)" (PDF). Proceedings of the Biological Society of Washington (Biological Society of Washington) 115 (4): 909–922. Retrieved 2008-06-12. 
  7. ^ Stevens, P (2001 onwards). "Angiosperm Phylogeny Website". Missouri Botanical Garden. Retrieved 2007-08-05.  Check date values in: |date= (help)
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Notes

Comments

Hecastocleis shockleyi is known from southwestern Nevada and adjacent California.
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