Hecastocleis

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Hecastocleis
Hecastocleis shockleyi flowering heads.jpg
Hecastocleis shockleyi flowering heads
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Hecastocleidoideae
Panero & V.A.Funk
Tribe: Hecastocleideae
Panero & V.A.Funk
Genus: Hecastocleis
A.Gray
Species:
H. shockleyi
Binomial name
Hecastocleis shockleyi
A.Gray

Hecastocleis is a genus of low thorny shrubs with stiff branches, assigned to the daisy family. At the tip of each of the branches, inflorescences are subtended by oval, thorny, whitish to greenish bracts that enclose several flower heads which each contain only one pinkish bud, opening into a white corolla. It contains but one species, Hecastocleis shockleyi, the only representative of the tribe Hecastocleideae, and of the subfamily Hecastocleidoideae. Its vernacular name is prickleleaf. It is confined to the southwestern United States. [1]

Contents

Description

Hecastocleis shockleyi is a xerophytic thorny shrub of 40–70 cm (1.3–2.3 ft), occasionally 1½ m (4 ft 11 in) high. It has sixteen chromosomes (2n=16). [1]

Leaves

The leaves are alternately set along the branches. The leaf blades are hairless or with a few soft hairs, slightly olive green, stiff and leathery, with three main veins, linear to narrowly ovate in shape, 1–4 cm (0.39–1.57 in) long, their base approximately clasping the branch, with thickened margins usually carrying three to six spines of 1–3 mm (0.039–0.118 in) long, denser spaced near the base, while the tip is more or less abruptly tapering into a point. [1]

Inflorescence

The complex inflorescences are carried at the end of the branches. These consist of a number of crowded clusters. Each of the clusters is subtended by white to yellowish green, wavy, ovate to orbicular bracts that have a spiny margin, and further consist of one to five flower heads which each contain only a single disk floret. The most outward part of the flower head is the involucre, which is narrowly vase-shaped to cylindric and approximately 1 cm (0.39 in) high, and consists of about six worls of four bracts called phyllaries, which have often soft woolly hairs around the edge. The base of the flower head (or receptacle) is flat and lacks a bract directly at the base of the floret. The corolla of the florets is pinkish purple when still in bud, but turns pinkish white at flowering, at which time it is about 1 cm (0.39 in) high. These are hermaphrodite, star-symmetric (or actinomorphic), and have five narrow outwards oriented lobes. The five pinkish purple anthers are fused into a long tube, that initially covers the entire style. The bone-colored style grows through the anther tube, collecting the pollen on hairs, and displaying it above the anter tube like in all other Asteraceae. The style branches are only 0.1–0.5 mm (0.0039–0.0197 in) and have rounded tips. At the base of the corolla the one-seeded indehiscent fruit (called cypselas) develops, which is not flattened, has four to five hardly visible nerves, turns brown and has lost any hairs when ripe, and is about ½ cm (0.2 in) high. On the top of the cypselas is a crown of six unequal scales (the pappus) of 1–2 mm (0.039–0.079 in) high. These scales are lanceolate in shape, may have several teeth and are sometimes fused at their base, so forming a crown. The pollen of Hecastocleis is yellow, unadorned and tricolpate. [1]

Differences with other Asteraceae

Like Hecastocleis, some other Asteraceae also have flower heads consisting of a single floret, such as Gundelia , a perennial herbaceous plant from the Middle-East, and Gymnarrhena a winter annual from northern Africa and the Middle-East. Both have male flowers and female flowers, not hermaphrodite as in Hecastocleis, while Gymnarrhena has (trimerous or) tetramerous male florets, not pentamerous.

Taxonomy

Hecastocleis shockleyi was described by Asa Gray in 1882 and placed it to the tribe Mutisieae. Kåre Bremer in 1994 assigned it to the subtribe Mutisiinae, while Hind in 2006 erected its own group within the Mutisieae. [1]

Modern classification

Scholars agree that Hecastocleis occupies a very isolated position on the evolutionary grade of subfamilies of the Asteraceae, and this is expressed by the erection of the monotypic subfamily Hecastocleidoideae. [2]

Phylogeny

The current insights in the relationships between Hecastocleis and its closest relatives, as based on genetic analysis, is expressed in the following tree.

Gochnatioideae

Hecastocleis shockleyi

Carduoideae

Pertyoideae, Gymnarrhenoideae, Cichorioideae, Corymbioideae, Asteroideae

Biogeology

Earlier splits of the Asteraceae tree are supposed to have taken place in southern South America. The splits that occur later than Hecastocleis have occurred Africa, especially southern Africa, and some may also have occurred in Asia. This implies that the common ancestor of Hecastocleis and all later branches moved from South America to North American and after the split with Hecastocleis, the ancestor of the remainder of the subfamilies arrived in Africa from North-America. Alternatively, only the ancestor of Hecastocleis migrated from South America to North America while the ancestor of the remainder was distributed from South America to Africa. The placement of Hecastocleis in the tree could also be incorrect due to parallel evolution an reversal of earlier mutations. However, the support in the analysis for the separation of Hecastocleis from the Gochnatieae is strong. [1]

Etymology

The name of the genus Hecastocleis is the contraction of two Greek words, ἕκαστος (hekastos) meaning "each" and κλειω (kleio) which is said to mean "to shut up", referring to each flower having its own involucre. An alternative meaning of kleio is "glory". The species was named shockleyi in honor of William Hillman Shockley, an early plant collector of the flora of Nevada and father of the co-inventor of the transistor William Shockley. [1]

Distribution

Prickleleaf is native to the desert plains and mountains of eastern California (Inyo, Mono, Kern, and San Bernardino Counties) and southern Nevada (Mineral, Esmeralda, Nye, Lincoln, and Clark Counties), where it grows on arid, rocky slopes and flats. [3] [4] [5] [6] Records of this plant include Mount Charleston, Nevada Test Site, Grapevine Mountains and Red Pass. [1]

Ecology

In the mountains rimming the north-side of Death Valley, Hecastocleis shockleyi may be one of the dominant shrubs together with Atriplex confertifolia , Eriogonum fasciculatum , and Tetradymia axillaris . Less dominant but often present shrubs are Ephedra viridis , Ericameria laricifolia , and Lepidium fremontii . Trees are absent. Herbaceous plants form an open layer and regularly include the grasses Achnatherum hymenoides , Bromus rubens and Poa secunda , in addition to Claytonia perfoliata , Cryptantha utahensis , Delphinium parishii, several Gilia species, and Phacelia vallis-mortae . Biological soil crust, lichen, and moss can also be found in this plant community. It is found primarily on steep, very rocky slopes and bedrock outcrops with northerly aspects. Hecastocleis shockleyi occurs at altitudes between 1250 and 1600 m. It typically grows on calcareous clay loam, loamy sand, or sandy clay that has resulted from erosion of dolomite, limestone or shale, and is poor in nutrients. [7] Pollination of Hecastocleis has not yet been observed, but as its flowers are white, nocturnal insects are likely candidates. [8]

Related Research Articles

Asteraceae Large family of flowering plants

The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae were first described in the year 1740. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger family is unclear as the quantity of extant species in each family is unknown.

<i>Scolymus</i> Genus of flowering plants

Scolymus is a genus of annual, biennial or perennial, herbaceous plants that is assigned to the Daisy family, and can be found in Macaronesia, around the Mediterranean, and in the Middle East. All species are spiny, thistle-like in appearance, with flowerheads that consist of yellow ligulate florets, and canals that contain latex. It is known as سكوليمس (skwlyms) in Arab, scolyme in French, and is sometimes called golden thistle or oyster thistle in English.

<i>Scolymus maculatus</i> Species of flowering plant

Scolymus maculatus is a spiny annual plant in the family Asteraceae, native to the Mediterranean region in southern Europe, southwest Asia, and northern Africa, and also the Canary Islands. It has pinnately incised prickly leaves and prickly wings along the stems, both with a white marginal vein. The yellow flowerheads stand solitary or with a few together at the tip to the stems, and subtended by more than five leaflike bracts. The plant is known as scolyme taché in French, cardogna macchiata in Italian, cardo borriquero in Spanish, and escólimo-malhado in Portuguese, חוח עקוד in Hebrew and سنارية حولية in Arabic. In English it is called spotted golden thistle or spotted oyster thistle.

<i>Polyarrhena</i>

Polyarrhena is a genus of low, branching shrublets that is assigned to the daisy family. Its stems are alternately and densely set with entire or somewhat toothed leaves. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and which are surrounded by an involucre of in this case three whorls of bracts. In Polyarrhena, the centre of the head is taken by yellow disc florets, and is surrounded by one single whorl of white ligulate florets that have a pinkish-purple wash on the underside. These florets sit on a common base and are not individually subtended by a bract. The species occur in the Cape Floristic Region. Polyarrhena reflexa has long been cultivated as an ornamental and is often known under its synonym Aster reflexum.

<i>Gorteria</i>

Gorteria is a genus of small annual herbaceous plants or shrubs, with 8 known species, that is assigned to the daisy family. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and are surrounded by an involucre, consisting of in this case several whorls of bracts, which are merged at their base. In Gorteria, the centre of the head is taken by relatively few bisexual and sometimes also male, yellow to orange disc florets, and is surrounded by one complete whorl of 5–14 infertile cream to dark orange ray florets, sometimes with a few ray florets nearer to the centre. None, some or all of them may have darker spots at their base. The fruits remain attached to their common base when ripe, and it is the entire head that breaks free from the plant. One or few seeds germinate inside the flower head which can be found at the foot of plants during their first year. The species flower between August and October, except for G. warmbadica that blooms mostly in May and June. The species of the genus Gorteria can be found in Namibia and South Africa.

<i>Gymnarrhena</i> Genus of flowering plants

Gymnarrhena is a deviant genus of plants in the daisy family, with only one known species, Gymnarrhena micrantha. It is native to North Africa and the Middle East, as far east as Balochistan. Together with the very different Cavea tanguensis it constitutes the tribe Gymnarrheneae, and in the subfamily Gymnarrhenoideae.

Warionia is a genus in the dandelion tribe within the daisy family. The only known species is Warionia saharae, an endemic of Algeria and Morocco, and it is locally known in the Berber language as afessas, abessas or tazart n-îfiss. It is an aromatic, thistle-like shrub of ½–2 m high, that contains a white latex, and has fleshy, pinnately divided, wavy leaves. It is not thorny or prickly. The aggregate flower heads contain yellow disk florets. It flowers from April till June. Because Warionia is deviant in many respects from any other Asteraceae, different scholars have placed it hesitantly in the Cardueae, Gundelieae, Mutisieae, but now genetic analysis positions it as the sister group to all other Cichorieae.

<i>Catamixis</i> Genus of flowering plants

Catamixis is a genus assigned to the daisy family, with only one known species, Catamixis baccharoides, a low to medium height, ¾—1¾ m, shrub. It is native to a very small area of western Nepal and northern India in the Himalayas. It has approximately spoon-shaped, leathery leaves with distanced rounded teeth alternately set along straight, shyly branching stems, and carries many flower heads of about 1 cm, with a few creamy white florets, sometimes with a hint of violet, in corymbs at the end of the branches. Flowers and fruits can be found between March and May. Its vernacular name in Hindi is विषपत्री (vishpatri) or विश्पत्र (vishpatra).

Cavea is a low perennial herbaceous plant that is assigned to the daisy family. Cavea tanguensis is currently the only species assigned to this genus. It has a basal rosette of entire, slightly leathery leaves, and stems of 5–25 cm high, topped by bowl-shaped flower heads with many slender florets with long pappus and purplish corollas. The vernacular name in Chinese is 葶菊. It grows high in the mountains of China (Sichuan), Tibet, India (Sikkim), and Bhutan, and flowers in July and August.

Stifftioideae Subfamily of flowering plants

The Stifftioideae are a subfamily of the Asteraceae, or sunflower family, of flowering plants. It comprises a single tribe, Stifftieae, of ten genera.

<i>Gorteria diffusa</i> Annual plant in the daisy family from South Africa

Gorteria diffusa is a highly variable, small annual herbaceous plant or rarely a shrublet that is assigned to the daisy family. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and are surrounded by an involucre, consisting of in this case several whorls of bracts, which are merged at their base. In G. diffusa, the centre of the head is taken by relatively few male and bisexual yellow to orange disc florets, and is surrounded by one complete whorl of 5–14 infertile cream to dark orange ray florets, sometimes with a few ray florets nearer to the centre. None, some or all of them may have darker spots at their base. The fruits remain attached to their common base when ripe, and it is the entire head that breaks free from the plant. One or few seeds germinate inside the flower head which can be found at the foot of plants during their first year. The species flowers between August and October. It is called beetle daisy in English and katoog in Afrikaans. It can be found in Namibia and South Africa.

<i>Scolymus grandiflorus</i> Species of flowering plant

Scolymus grandiflorus is a spiny annual or biennial plant in the family Asteraceae, native to the Mediterranean region. With up to 75 cm high stems, it is the smallest of the species of Scolymus. Its stems are lined with uninterrupted spiny wings. It also has the largest flowerheads in the genus, of approximately 5 cm wide. It has yellow, sometimes yolk-yellow ligulate florets. Its vernacular name in Maltese is xewk isfar kbir, meaning "large yellow fin", cardogna maggiore in Italian, scoddi on Sicily, and scolyme à grandes fleurs in French.

Catananche lutea, is a woolly annual plant, assigned to the daisy family, with most leaves in a basal rosette, and some smaller leaves on the stems at the base of the branches. Seated horizontal flowerheads develop early on under the rosette leaves. Later, not or sparingly branching erect stems grow to 8–40 cm high, carrying solitary flowerheads at their tips with a papery involucre whitish to beige, reaching beyond the yellow ligulate florets. Flowers are present between April and June. This plant is unique for the five different types of seed it develops, few larger seeds from the basal flowerheads, which remain in the soil, and smaller seeds from the flowerheads above ground that may be spread by the wind or remain in the flowerhead when it breaks from the dead plant. This phenomenon is known as amphicarpy. The seeds germinate immediately, but in one type, germination is postponed. It naturally occurs around the Mediterranean. Sources in English sometimes refer to this species as yellow succory.

Famatinanthus is a genus in the family Asteraceae that was described in 2014 and has been assigned to its own tribe Famatinantheae and subfamily Famatinanthoideae. It contains only one known species, F. decussatus, a small shrub of ½—1¾ m high that is an endemic of the Andes of north-western Argentina, with small, entire, oppositely set leaves and flowerheads containing about ten cream-colored, ray and disk florets, with backward coiled lobes. It is locally known as sacansa. For more than 100 years, the species was known to science only from the type collection. It was described in 1885 and originally assigned to the genus Aphyllocladus.

<i>Felicia echinata</i> Shrublet in the daisy family from South Africa

Felicia echinata, commonly known as the dune daisy or prickly felicia, is a species of shrub native to South Africa belonging to the daisy family. It grows to 1 m (3.3 ft) high and bears blue-purple flower heads with yellow central discs. In the wild, it flowers April to October.

<i>Felicia josephinae</i> An annual plant in the daisy family from South Africa

Felicia josephinae is a roughly hairy annual herbaceous plant of 15–20 cm (6–8 in) high, that is assigned to the family Asteraceae. It branches near its base, and has few leaves along its stems. The lower leaves are set oppositely, inverted lance-shaped, relatively large at 3–7 cm long and ⅔–1¼ cm wide, and soon withering, while the higher ones are smaller and relatively narrower. In the axils of the leaves grow flower heads of 7–8 mm wide on stalks of up to 5 cm (2 in) long, topped with an involucre of about 5 mm (0.2 in) high and 4 mm (0.16 in) wide, consisting of eleven to thirteen bracts in two rows with bristles near the tip, eight to nine white or cream-coloured ligulate florets surrounding fourteen or fifteen deep purple disc florets. Flowers can be found in September and October. The species is an endemic species that can only be found in a small area along the west coast of the Western Cape province of South Africa.

<i>Felicia macrorrhiza</i> A shrublet in the daisy family from South Africa

Felicia macrorrhiza is a small, evergreen shrub in the family Asteraceae. This species grows in the Karoo region of South Africa. It is called Aspoestertjie in Afrikaans.

<i>Felicia nordenstamii</i> A shrublet in the daisy family from South Africa

Felicia nordenstamii is a flowering shrub in the family Asteraceae. It is found only in South Africa where it grows on limestone hills close to the sea on the southern coast. Felicia nordenstamii is a many-branched shrub growing up to 30 cm (1 ft) tall. The lower parts of the stems are covered in grayish brown bark and the upper stem has many crowded, upwardly angled, alternate leaves with long hairs on the lower surfaces. Large flower heads form at the tips of the branches, each about 412 cm across, with about thirty purplish blue ray florets surrounding many yellow disc florets.

Felicia westae is a sparsely branched shrub growing up to 40 cm tall, that is assigned to the family Asteraceae. The lower parts of the stems have lost their leaves and the upper part has many crowded, upwardly angled and curved, alternate leaves pressed against the stem, with the edges curled inward. The flower heads form at the tips of the branches, each about 313 cm across, with about twenty purplish blue ray florets surrounding many yellow disc florets. It is only known from a small area in the Eastern Cape province of South Africa.

Felicia clavipilosa is an upright, richly branched shrub of up to 60 cm (2 ft) high, that is assigned to the family Asteraceae. It has alternately arranged leaves, and flower heads with 3–4 whorls of involucral bracts with many yellow disc florets in the centre. Very characteristic for the species are the short club-shaped hairs on its fruits. There are two subspecies. Subsp. clavipilosa has narrowly lance-shaped entire leaves with one vein and pale mauve ray florets. Subspecies transvaalensis has lance-shaped leaves with one or three veins and white ray florets. The species occurs in southern Africa, with subsp. clavipilosa having a western distribution in Zambia, Zimbabwe, Namibia, Botswana and South Africa, and subsp. transvaalensis restricted to the east, from Zimbabwe, through Botswana to South Africa. The subspecies transvaalensis is sometimes called pokkiesblom in Afrikaans.

References

  1. 1 2 3 4 5 6 7 8 "Hecastocleis shockleyi A. Gray". Encyclopedia of Life. Retrieved 2016-01-02. and Funk, Vicki A.; Hind, D.J. Nicholas. "Chapter 16. Hecastocleideae (Hecastocleidoideae)". In V.A. Funk; A. Susanna; T. Stuessy; R. Bayer (eds.). Systematics, Evolution, and Biogeography of Compositae (PDF). Vienna: International Association for Plant Taxonomy . Retrieved 2016-01-02.
  2. Panero, Jose L.; Funk, Vicki A. (2009), "New tribes in Asteraceae", Phytologia, 91 (3): 568–570
  3. Biota of North America Program 2013 county distribution map
  4. Flora of North America, Vol. 19, 20 and 21 Page 71, Hecastocleis A. Gray
  5. "Shockley's prickleleaf". Calflora. Retrieved 2017-01-03.
  6. Cronquist, A.; Holmgren, A.H.; Holmgren, N.H.; Reveal, J.L.; Holmgren, P.K. (1994). Intermountain Flora: Vascular Plants of the Intermountain West, U.S.A. Vol. 5. New York Botanical Garden. pp.  422, 425. ISBN   0-89327-375-9.
  7. "Association Detail Report: CEGL005467 - Hecastocleis shockleyi Shrubland". USNVC. Retrieved 2016-01-02.
  8. Vogel, Stefan (2015). "Vertebrate Pollination in Compositae: Floral Syndromes and Field Observations". Stapfia. 103: 5–26.