Receptacular Bracts Research Articles

Possible phylogenetic relationships of Gymnarrhena (Gymnarrheneae, Gymnarrhenoideae, Asteraceae) based on comparative carpology

The amphicarpic annual Gymnarrhena micrantha (Asteraceae), inhabiting the deserts of North Africa to the Middle East, is interesting not only for its unusual biology, but also for its peculiar morphological structure. The monotypic genus Gymnarrhena, with uncertain position in the Asteraceae for a long time, is currently included in the tribe Gymnarrheneae and a separate subfamily Gymnarrhenoideae. The objective of the study was to examine fruit and seed structure in G. micrantha to consider possible phylogenetic relationships of the genus based on carpological characters. It was found that fruit structural organization in G. micrantha, with simply arranged pericarp and seed coat, parenchymatous and poorly differentiated on the tissue, corresponds to that of the early diverging evolutionary lines of Asteraceae, in which the states of these characters are considered to be plesiomorphic in the family. It has been suggested that taxonomically important structural features of Gymnarrhena cypsela include the structure of the apical region, pericarp and seed coat, the place of pappus attachment and its structure, the type of pappus hygroscopic tissue, and morphophysiological features of receptacular bracts surrounding the cypsela. The study did not confirm the relationship of Gymnarrhena with the tribes Corymbieae and Cichorieae, the seed coat of which differs markedly from the seed coat of Gymnarrhena in the presence of fine porosity of the exotesta cell walls. A set of the anatomical and carpological characters indicates a possible relationship of Gymnarrhena with the basal subtribes Cardopatiinae and Carlininae of the tribe Cardueae. The morphophysiological adaptation of G. micrantha and Cousiniopsis atractyloides cypselae to dissemination in desert conditions, similar in structural details, apparently suggests a close relationship between the subfamilies Gymnarrhenoideae and Carduoideae.

A taxonomic revision of the genus Cephalaria (Caprifoliaceae) in Turkey

The morphological features of Cephalaria Schrad. ex Roem. & Schult. were studied based on our specimens collected between 1994 and 2010 in Turkey and herbarium specimens from various herbaria. In the present study, typifications, a list of synonyms, descriptions, ecology, phytogeographical regions, conservation status, and distribution of all studied taxa are given. Taxonomic relationships between similar species are discussed. Illustrations of habit, flower, calyx, involucel, and involucral and receptacular bracts of some species are given. Colour images of some species are also provided. Additional new characters were determined that were not previously given in descriptions of Cephalaria species in the Flora of Turkey, and a new identification key has been prepared for the Turkish species. In addition, Cephalaria demirizii Göktürk & Sümbül is given as a new species from Turkey, while C. amana Rech.f. is made a synonym of C. taurica Szabó. Lectotypes are designated for C. transylvanica (L.) Schrad., C. cilicica Boiss. & Kotschy, C. setosa Boiss. & Hohen., C. sparsipilosa V.A.Matthews, and C. taurica.

Comparative ontogeny of perfect and pistillate florets in Senecio vernalis (Asteraceae)

We studied the inflorescence, and in particular ontogeny and development of the florets in Senecio vernalis as a representative member of Asteraceae, using epi-illumination microscopy. Initiation and subsequent development of florets on the highly convex inflorescence apex occur acropetally, except for pistillate ray florets, which show a lag in initiation. Receptacular bracts derive from the receptacular surface after development of all florets. The order of whorl initiation in both disc and ray florets include corolla, androecium and finally the pappus, together with the gynoecium. Development of corolla lobes from a ring meristem occurs in bidirectional order starting from the lateral side, whereas stamens incept unidirectionally from the abaxial side. Concurrently with the inception of two median carpel primordia, a ring meristem develops at the base of the corolla from which pappus bristles differentiate in later stages. Pistillate ray florets show significant differences from perfect disc florets as reflected by the zygomorphic shape of the floral apex and a shift of floral merosity from pentamery to tetramery. Loss of stamens in ray florets occurs due to abortion of primordia after initiation.

The development of pistillate and perfect florets in Xeranthemum squarrosum (Asteraceae)

The formation of capitulum inflorescence with two different types of floret is an interesting issue in floral biology and evolution. Here we studied the inflorescence, floral ontogeny and development of the everlasting herb, Xeranthemum squarrosum, using epi-illumination microscopy. The small vegetative apex enlarged and produced involucral bracts with helical phyllotaxy, which subtended floret primordia in the innermost whorl. Initiation of floret primordia was followed by an acropetal sequence, except for pistillate peripheral florets. The origin of receptacular bracts was unusual, as they derived from the floral primordia rather than the receptacular surface. The order of whorl initiation in both disc and pistillate flowers included corolla, androecium and finally calyx, together with the gynoecium. The inception of sepals and stamens occurred in unidirectional order starting from the abaxial side, whereas petals incepted unidirectionally from the adaxial or abaxial side. Substantial differences were observed in flower structure and the development between pistillate and perfect florets. Pistillate florets presented a zygomorphic floral primordium, tetramerous corolla and androecium and two sepal lobes. In these florets, two sepal lobes and four stamen primordia stopped growing, and the ovary developed neither an ovule nor a typical stigma. The results suggest that peripheral pistillate florets in X.squarrosum, which has a bilabiate corolla, could be considered as an intermediate state between ancestral bilabiate florets and the derived ray florets.

A New Species of Dubautia (Asteraceae-Madiinae) from Kaua'i, Hawaiian Islands

Dubautia kenwoodii G. Carr from the Hawaiian Island of Kaua'i is described and illustrated. The new species is distinguished from congeners by virtue of its combination of uniseriate, peripheral, very firmly coalescent receptacular bracts, cymose-glomerate capitula, and coriaceous, lustrous leaves with sharply cartilaginous-toothed margins and abruptly narrowed, broadly clasping bases. Intensive botanical exploration of Kaua'i over the last several years has led to increased understanding of many plant groups and to the discovery of many species not previously known to science. For example, the publication of a new species of Dubautia from Kaua'i by Carr and Lorence (1998, this issue), brings the total number of species currently recognized in that genus to 22 (cf. Carr, 1985). The substantial body of new information about Dubautia on Kaua'i warrants a detailed reassessment of the genus on that island. However, it seems more prudent to formally recognize another new, exceedingly rare species of Dubautia in a timely fashion in order to encourage efforts to find additional populations of this critically endangered taxon and to make it eligible for legal protection and conservation. Dubautia kenwoodii G. Carr, sp. nov. TYPE: Hawaiian Islands (U.S.A.). Kaua'i: Hanalei District, Kalalau Rim, N of Kahuama'a Flat, steep, diverse Lowland Mesic Forest, 800 m, 4 July 1991. K. R. Wood & M. Query 1004 (holotype, PTBG). Figures 1, 2. A speciebus aliis Dubautiae sectionis Dulbautiae bracteis receptaculi uniseriatis peripheralil)us firmissimis coalescentibus, c(apitulis cymnoso-glomerulaltis. foliis (o?riaceis nitidis margine acute cartilaginidentata l)asi al)rupte contracta dliffert. Shrub 5 dm tall, vegetative stems apparently glabrous except for a tuft of trichomes on the upper border of some leaf scars, woody and brown below; flowering stems becoming increasingly hispid in the region of the capitulescence. Leaves opposite, coriaceous, commonly 4-12 cm long, 0.8-2.0 cm broad, narrowly elliptic to sometimes narrowly lanceolate, surfaces nearly concolorous in dried material, gray-green, lustrous above, only slightly paler and duller beneath, glabrous, or becoming medially hispidulous in proximity to the capitulescence: margins with very conspicuous sharply pointed, narrow, somewhat cartilaginous teeth from apex to about the middle, often ciliolate basally; apex usually slightly acuminate; base rather abruptly narrowed and somewhat broadly clasping the stem at point of insertion; venation parallelodromous, with mostly 7 basal veins visible above, sometimes with additional parallel veins and usually fainter elongate-areolate reticulations visible beneath. Heads numerous, disposed in elongatepaniculiform, cymose-glomerate congested capitulescences about 14 cm long and 10 cm broad; peduncles increasingly hispidulous above, the ultimate ones mostly less than 1 mm long; receptacular bracts about 9-12, linear-oblanceolate, gray-green, densely hispidulous and obscurely minutely glandular, peripheral, uniseriate, the lower 23 very strongly and uniformly coalescent (remaining so and becoming sub-indurate on drying), forming a cone about 5 mm long, the lanceolate free tips up to 3 mm long, apparently reflexed in age; receptacle flat, moderately hirsute between the fruit scars; florets mostly 12-18, the corolla rusty yellow in age, 3.0-4.0 mm long, apparently commonly slightly exceeded by the pappus, moderately glandular on the tubular portion, rather abruptly dilated distally, ending in 5 triangular lobes about 1 mm long; pappus stramineous, comprising about 21 unequal, very narrowly linear-lanceolate, shortly fimbriate aristae 3.75-4.5 mm long; achenes conspicuously grayish-strigose, straight or only slightly curved, mostly 3.5-4.5 mm long. Distribution. This taxon is known only from a single collection on the steep slopes of the Kalalau Rim where it was reached by rappelling. Based on extremely limited phenological data, flowering appears to occur in June. Habitat. Dubautia kenwoodii is found in a diverse Lowland Mesic Forest community with Chamaesvce eleanoriae Lorence & W. L. Wagner, HedNovoN 8: 8-11. 1998. This content downloaded from 207.46.13.133 on Fri, 22 Jul 2016 03:58:58 UTC All use subject to http://about.jstor.org/terms 9 Volume 8, Number 1 1998 Carr Dubautia kenwoodii from Kaua'i

THE ADAPTIVE AND PHYLOGENETIC SIGNIFICANCE OF RECEPTACULAR BRACTS IN THE COMPOSITAE

SummaryMany morphological features of the heads of Compositae are systematically useful. Receptacular bracts (pales or paleae) are of particular significance taxonomically. These structures occur in nine of the 13 recognized tribes (absent in Arctoteae, Calenduleae, Senecioneae and Tageteae), with the greatest concentration in the Anthemideae, Heliantheae, and Inuleae. Because the Heliantheae contain the broadest diversity of pale types, the adaptive significance of these features within this tribe deserves special emphasis. Certain subtribes of the Heliantheae are characterized by distinctive types of pales, such as flattened with orange‐brown lines in the Coreopsidinae, pales subtending only the outer series of disc florets in the Madiinae, or their complete absence in the Bahiinae. Of the five principal factors affecting the evolution of features of heads in the family, viz., protection, dispersal, pollination, breeding systems, and seed germination, the former two are most likely the most important selective forces in the evolution of pales. Dispersal functions of pales include attachment or close envelopment of the achene by the pales with removal of the entire unit by wind from the head, conduplicate pales serving as chutes for release of unattached achenes, and brightly colored, fleshy pales being attractive to animals. Protective functions occur against predators and environmental extremes, and occur in bud, anthesis, and mature fruiting stages. Pales function during anthesis to protect ovaries and achenes from apical and lateral insect attack. The particular variations of the pales depend on the associated structures of the heads and breeding systems. In a phylogenetic context, the large and sometimes foliose pales of the Heliantheae seem best interpreted as adaptations for protection of large achenes and not necessarily as reflections of a primitive condition within the family.

Untersuchungen zur Morphologie der Involukral- und Spreublätter der Gattung Carlina L.

The involucral and receptacular bracts of Carlina acaulis L. as well as of some other species of the genera Carlina L. and Atractylis L. have been investigated from the viewpoint of comparative morphology. The upper foliage leaves and the involucral bracts of Carlina acaulis L. represent a continuous row of forms. From the upper foliage leaves to the middle involucral bracts an increasing shortening of the leaves takes place. In the course of the transition from the outer to the middle involucral bracts the branched thorny leaflets of the outer involucral bracts are changed into slender soft bristles, which are reduced in the following bracts totally. The transition to the inner involucral bracts is characterized by extension of the lamina and the leaf-base. The marginal florets are inserted in the axil of the inner involucral bracts. They possess several bristly receptacular bracts arranged singly or in groups of two or three on both sides of the floret median. The other florets of the capitulum not originating in an axil of a leaf possess two or three bristly receptacular bracts arranged in the floret median in the outer semicircle of the floret periphery. The outermost of the last mentioned bracts can be a subunifacial one. Correspondences in the developmental sequence of the florets as well as in numerous bract characters refer to a homology in the inflorescences of the genera Carlina L. and Echinops L. In contrast to the floret of the genus Echinops L., characterized by numerous bracts regularly distributed around the floret, in the genus Carlina L. the bract number is much diminished and the distribution of the bracts is confined to few sectors of the floret periphery.

Kritische Evaluation zur Deutung der Spreublattkomplexe von Carlina L.

Summary It is shown by meticulous pattern analysis that there are, theoretically, good reasons for the assumption that the receptacular bracts in Carlina can be taken as residuals of a more complex inflorescence (syncephalium) which has been reduced under evolution.

Taxonomy of Hemizonia sect. Madiomeris (Asteraceae: Madiinae)

Taxonomic review based on morphology, flavonoid chemistry, cytol- ogy, breeding experiments, and ecogeographic considerations suggests emendation of the circumscription of Hemizonia sect. Madiomeris and recognition of 17 taxa (14 species, one with two and one with three subspecies) within the section. New names are: Hemizonia increscens, H. increscens subsp. foliosa, and H. increscens subsp. villosa. Hemizonia martirensis, heretofore unassigned to a section, is included in sect. Madiomeris. Chromosome counts for 16 of the 17 taxa demonstrate an aneuploid series of n = 9, 10, 11, 12, and 13. Hemizonia sect. Madiomeris comprises 14 species distributed in the foot- hills and valleys from central California into Baja California Norte. Mem- bers of this section are distinguished from those in the other three sec- tions of the genus by one or more of the following characteristics: annual habit, beaked ray achenes, lack of apiculations on leaves and phyllaries, and receptacular bracts usually confined to an outer connate ring. The concept of sections in Hemizonia originated with de Candolle (1836) when he described the sections Madarioides and Olocarpha. Section Madarioides contained H. congesta and H. angustifolia while sect. Olocarpha contained H. luzulaefolia and H. macradenia. De Candolle (1836) also described the genus Hartmannia (non Spach 1835) containing three species: H. corymbosa, H. fasciculata, and H. ciliata. Torrey and Gray (1843) treated the species of Hartmannia under Hemizonia. They neither recognized the sections of de Candolle, nor did they offer any sectional designations of their own. Six groups of species, however, were denoted by being set off by printer's marks. Nuttall (1848) circumscribed the sect. Madiomeris to include a new species, Hemizonia macrocephala Nutt., but did not provide any evidence as to its relationship to any other sections in the genus. Gray (1874) named four subgenera under Hemizonia, of which one was Hartmannia DC., including H. angustifolia and H. macradenia within the subgenus. He circumscribed the subgenus Euhemizonia to include only H. congesta and H. luzulaefolia. Greene (1897) transferred H. an- gustifolia and H. corymbosa to a segregate genus Zonanthemis. He also moved all species of Hemizonia subg. Hartmannia to the segregate genus Deinandra, noting that Hartmannia DC. (1836) was a later homonym of Hartmannia Spach (1835). Greene (1897) treated sect. Olocarpha DC. (Holocarpha is orthographically correct) as a distinct genus, including within it, H. macradenia. Jepson (1925) and Munz (1935) did not recog-

Systematics of Isocarpha (Compositae: Eupatorieae)

Isocarpha comprises five species ranging from southern Texas and the Bahamas to northern Peru and northeastern Brazil. The genus belongs in Eupato­ rieae rather than Heliantheae, but structure of the head of Isocarpha with its elon­ gate, chaffy receptacle is anomalous within Eupatorieae. An hypothesis is presented suggesting the evolutionary derivation of this type of head through formation of floral buds in the axils of the involucral bracts. Generic ties of Isocarpha within Eupatorieae are unclear, but the closest affinities appear to be with Ayapana and relatives. Isocarpha is a small g~nus of Latin American Compositae occurring principally within Mexico, Central America, the Caribbean, and northern South America. Taxonomic problems at the specific and varietal levels have persisted for many years, but more vexing have been questions of generic, subtribal, and tribal affinities. Isocarpha has been treated as be­ longing both to Eupatorieae (Robinson and King 1977) and Heliantheae (Stuessy 1977). Part of this difficulty of tribal placement has derived from the unusual conical receptacle and lack of differentiation between in­ volucral and receptacular bracts. These problems suggested the need for' a modern revision with focus on reproductive morphology and tribal and generic affinities. TAXONOMIC HISTORY Isocarpha was first recognized by Robert Brown (1817) who formed the genus to accommodate two Linnaean species, Galea opPositifolia and Spi­ lanthus atriplicifolius, that were discordant elements in the genera to which they had originally been assigned. Cassini (1822, 1823) suggested that Isocarpha be placed in Heliantheae and added two additional species (I. kunthii and I. pyrethraria), both of which we have excluded from the genus. i.Lessing (1830), believing Brown's Isocarpha to be congeneric with Gal- ydermos Lagasca (=Galea L., Heliantheae), described as new his own ver­ sion of Isocarpha in which he included a new species, I. echioides. This taxon was later transferred by Hemsley (1881) to Ageratum (Eupatorieae). In 1831, Lessing reversed his opinion and merged his own version of Isocarpha with that of Brown and added to it another new spe~ies (I. billbergiana). In the same publication (Lessing 1831) he noted that species

Calycadenia hooveri (Asteraceae), a New Tarweed from California

In accord with its cytological and morphological distinctiveness and its geographical disjunction, the Sierran element ofC. pauciflora A. Gray is described as a new species,C. hooveri. Its chromosome number ofn = 7 is documented for the first time. Evidence from cytogenetic analysis of synthetic hybrids is presented to support the conclusion thatC. hooveri is more closely related toC. villosa DC. than toC. pauciflora. Characteristics of ligule morphology and the distribution of the peculiar saucer-shaped glands on the peduncular and receptacular bracts of these species also support the new interpretation.

Seed Germination, and Growth and Development of Rudbeckia occidentalis Nutt. (Western Coneflower) on Aspen Range in Utah

Germination as affected by temperature and light, seed- ling growth and survival, growth and development of mature plants, and the effects of clipping on survival and regrowth of Rudbeckia occidentalis Nutt. (western coneflower) on aspen range in northern Utah were inves- tigated. The success of the species as an important component of the aspen understory and in openings is attributed to abundant production of viable seed, high germinability under a wide range of temperature condi- tions, and vigorous growth of seedlings and mature plants. coarse, perennial herb of the Compositae (Heliantheae). It is distin- guished from related species by a columnar and discoidal receptacle, nonspinescent receptacular bracts, and corollas narrowed to short tubes at the base. The roots are thick and woody, and the caudex (Fig. 2) attains a diam of 30-60 cm in older plants. In the Intermountain region, the species grows in moist to moder- ately dry, shallow soil and occurs generally from the ponderosa pine zone up to and including the spruce zone (U.S.D.A. Forest Service, 1937). It is locally abundant in many areas throughout the aspen zone in Utah. Sampson (1923) and Houston (1954) considered the species to be an indicator of fair to poor conditions on mountain range, since soil erosion and impoverishment caused by overgrazing and other abuses extended its range and abundance. The aerial parts of western coneflower are generally unpalatable to livestock; however, because of the herb's abundance and large size, it is taken occasionally by sheep late in the season when other forage is reduced. It is utilized to a minor extent by big game.

Glandular Structures of Holocarpha and Their Ontogeny

Carlquist, Sherwin. (Rancho Santa Ana Botanic Garden, Claremont, California.) Glandular structures of Holocarpha and their ontogeny. Amer. Jour. Bot. 46(4): 300–308. Illus. 1959.—Two types of advanced glandular structures occur in the 4 species of the genus Holocarpha. Sessile disk-shaped glands occur at the tips of upper leaves and of involucral and receptacular bracts. Unlike all other glandular structures of Madinae which have been investigated, these originate from several protodermal initials rather than a single one. These glands, however, represent modifications of a glandular trichome. The other type of glandular structure, termed hollow-stalked trichome here, occurs on the outer surface of involucral and receptacular bracts. These trichomes originate from a single cell but differ from others in the formation of a hollow stalk, the wall of which is one cell in thickness. Mesophyll of the bract, often with an included vascular bundle, is present as an intrusion into the base of the hollow stalk. Corresponding to the advanced nature of the glandular structures, the leaves show specializations in the “inrolling” of margins. Upper leaves have a cylindrical organization of vascular tissue, whereas basal leaves are “normal” and leaves of the main stem are intermediate. The species of Holocarpha differ in certain details of leaf anatomy and structure of hollow-stalked trichomes. The systematic distribution of these is given. The essential unity of the various glandular structures of Madinae is discussed both in terms of mature structure and ontogeny, and the steps in the evolution of these are suggested.

GLANDULAR STRUCTURES OF HOLOCARPHA AND THEIR ONTOGENY

Carlquist, Sherwin. (Rancho Santa Ana Botanic Garden, Claremont, California.) Glandular structures of Holocarpha and their ontogeny. Amer. Jour. Bot. 46(4): 300–308. Illus. 1959.—Two types of advanced glandular structures occur in the 4 species of the genus Holocarpha. Sessile disk‐shaped glands occur at the tips of upper leaves and of involucral and receptacular bracts. Unlike all other glandular structures of Madinae which have been investigated, these originate from several protodermal initials rather than a single one. These glands, however, represent modifications of a glandular trichome. The other type of glandular structure, termed hollow‐stalked trichome here, occurs on the outer surface of involucral and receptacular bracts. These trichomes originate from a single cell but differ from others in the formation of a hollow stalk, the wall of which is one cell in thickness. Mesophyll of the bract, often with an included vascular bundle, is present as an intrusion into the base of the hollow stalk. Corresponding to the advanced nature of the glandular structures, the leaves show specializations in the “inrolling” of margins. Upper leaves have a cylindrical organization of vascular tissue, whereas basal leaves are “normal” and leaves of the main stem are intermediate. The species of Holocarpha differ in certain details of leaf anatomy and structure of hollow‐stalked trichomes. The systematic distribution of these is given. The essential unity of the various glandular structures of Madinae is discussed both in terms of mature structure and ontogeny, and the steps in the evolution of these are suggested.