A CYTOGEOGRAPHIC STUDY OF CHAENACTIS DOUGLASII (COMPOSITAE,HELENIEAE)

Analysis of 512 plants derived from 200 populations shows that the widely distributed western North American Chaenactis douglasii species-complex consists of diploids (n = 6), triploids, tetraploids, and hexaploids. Microsporocytes were the source of most of the chromosome counts. About 9% of all plants examined had one or more full-sized extra chromosomes. Multivalents, usually a ring or chain of four chromosomes, were almost entirely restricted to polyploids, where one or more were identified in 38% of the tetraploids and 33% of the hexaploids. With two exceptions, diploids and polyploids were not found in the same population. Frequencies of diploid, triploid, tetraploid, and hexaploid populations were, respectively, 34, 1.5, 55 and 9.5%. With significant exceptions, diploid populations predominate in the Pacific and Rocky Mountain Systems, whereas polyploid ones are most frequent in the intervening plateaus. Ploidy level is correlated with age of substrate, rather than with climate, elevation, vegetation, or soil type. Range, morphology, ploidy level, and meiotic behavior suggest that var. achilleifolia tetraploids and hexaploids are descendents of hybrids between other variants of the complex. The diploid-tetraploid-hexaploid geographic distribution and the age of the substrates where each tends to occur suggest that the complex evolved in late Cenozoic time in response to major climatic and geologic changes that induced migration and hybridization. The hybrid derivatives, stabilized by polyploidy and tolerant of increasing aridity, came to occupy newly available habitats in areas disturbed by volcanic activity and glacial or glacial-related processes.     

ARTIFICIAL HYBRIDIZATIONS IN THE SUBTRIBE PERITYLANAE (COMPOSITAE–HELENIEAE)

Artificial hybridizations were conducted with 37 species of four genera of the subtribe Peritylanae (Compositae). Crossability, pollen stainability, and meiotic behavior were examined for most of the resulting 61 F₁ hybrid combinations. Intergeneric hybrids involving Amauria, Eutetras, Pericome, and Perityle, and infrageneric hybrids involving Perityle were readily obtained. Lower crossability and hybrid fertility were displayed by intergeneric crosses. The infrageneric crosses of Perityle were organized into two categories, intersectional and infrasectional, based upon the taxonomic sections that are recognized for the genus; sect. Pappothrix, sect. Laphamia, and sect. Perityle. In general, the crossability and hybrid fertility of intersectional crosses was markedly higher than that of intergeneric crosses. The results suggest a closer relationship between the three taxonomic sections of Perityle than between Perityle and other genera of the subtribe.     

A STUDY OF MEIOSIS IN HAPLOPAPPUS GRACILIS (COMPOSITAE)

Jackson , R. C. (U. Kansas, Lawrence.) A study of meiosis Haplopappus gracilis (Compositae). Amer. Jour. Bot. 46(7): 550–554. Illus. 1959.—A study of meiosis in the two-paired Haplopappus gracilis has shown that each pair of chromosomes is easily recognized throughout the various stages of meiosis beginning with pachytene. A comparison of mitotic and meiotic chromosomes has been made, and the data indicate that a conspicuous heteropycnotic knob on chromosome B at pachytene is the nucleolar organizer. Other recognizable chromomeres were observed, but additional study is needed before a cytological map can be drawn to show whether regions other than those described on chromosome A and B may be used as markers.     

天南星科岩芋属的细胞地理学研究

本文报道了岩芋属三个种的染色体数目和核型:岩芋Remusatia vivipara是三倍体,核型公式为K(2n)=3X=42=42m;早花岩芋R. hookeriana为二倍体,核型公式为K(2n)=2X=28=22m(6SAT) 6m(2SAT);秀丽岩芋R. ornala,也是三倍体,核型公式为K(2n)=3X=42=36m(3SAT) 3sm 3st。在岩芋属中,岩芋是一个比较原始的种,秀丽岩芋较进化。岩芋属是热带非洲和热带亚洲间断分布的小属,它的原始类群岩芋(R. vivipara)的原始居群(二倍体居群)分布在印度南部,因而作者没想,古南大陆是岩芋属的起源地,本属向热带亚洲的扩散是与第三纪时喜马拉雅造山运动相联系的。     

A SYSTEMATIC REVIEW OF THE SUBTRIBE LAGASCEINAE (COMPOSITAE,HELIANTHEAE)

The subtribe Lagasceinae of the tribe Heliantheae is recognized traditionally to consist of two genera: Lagascea and Coulterella. Although both taxa possess uni-flowered heads aggregated into synflorescences, they are very different in most other morphological and anatomical respects. The six species of Lagascea that were investigated cytologically are n = 17, whereas the monotypic Coulterella is n = 18 with chromosomes one-half the size of those of Lagascea. The dissimilarities suggest that the two genera should not be retained in the same subtribe, and that the subtribe Lagasceinae should be abandoned. Lagascea seems to be related most closely to genera of the subtribe Helianthinae, such as Alvordia. Coulterella, on the other hand, seems closest to Flaveria of the tribe Helenieae or Senecioneae.     

A CLADISTIC ANALYSIS OF LUCILIA CASS. (COMPOSITAE, INULEAE)

Abstract— Lucilia is a South American genus with 23 species restricted to disjunct areas in southeastern Brazil and along the Andes. Lucilia is a monophyletic group defined by the co-occurrence of six characters: herbaceous, alternate-leaved, pappus with scabrid bristles fused at the base into a ring, style-branches with sweeping hairs far down, capitula sessile, and aseptate-flagellate hairs. A dadogram is presented using 41 morphological and anatomical characters arranged into 26 transformation series. The polarity of character states was determined by outgroup comparison with the genus Berroa. The cladistic analysis showed extensive parallel evolution in a number of the more conspicuous characters and produced four unresolved trichotomies. However, basing the hierarchy of Lucilia on the branching pattern produced by cladistic analysis results in a more natural and predicitive classification. Lucilia is divided into three sections, Lucilia, Intermedieae (sect, nov), and Lucilioides [divided into two subsections, Subspicata (subsect. nov.) and Lucilioides]. The latter subsection is subdivided into two series, Lucilioides (ser. nov.) and Paralucilia. The Brazilian species of section Lucilia (acutijolia, linearifolia, ferruginea, tmentosa, recurva, nitens, and flagelliformis) form the most primitive group within the genus. The more derived species of the genus, section lucilioides (plicatifolia, catamarcensis, burkartii, subspkata, lopezmirandae, alpina, pickeringii, piptolepis, santamca, chilensis, schultzii, longifolia, radians, lehmanni, pusilla) are found in the Andes L. eriophora (section Intermedieae) from central Chile bridges these two groups. An explanation for the distribution of the genus is given, based on the ecology of the species in relation to theories of the geologic and climatic history of South America. The present pattern has been determined by the age, geographical range, and vicissitudes of the habitat in which each group occurs. In the Brazilian species group, the habitat is old, and has remained relatively stable since well before the Pleistocene. In the Andean species group, the habitat is young and has undergone numerous rapid alterations since its inception at the end of the Pliocene.     

THE FLAVONOIDS OF LASTHENIA (COMPOSITAE)

Lasthenia (Compositae: Helenieae), a western North American-Chilean genus of 16 species, produces 22 flavonoid glycosides. Flavonoids are the chalcones butein and okanin, the aurones maritimetin and sulfuretin, the flavone luteolin, and the flavonols kaempferol, quercetin, and patuletin. The presence or absence of various of these classes of compounds in general follows sectional alignments in the genus, confirms affinities based on morphological and cytological evidence, and suggests relationships of problematical species. Intraspecific variation in flavonoid constituents occurs in several species, and in one taxon intrapopulation variation seems to exist as well. Evolution within Lasthenia has been associated with a loss of the ability to produce or accumulate luteolin, chalcones, and aurones; an increase in diversity of quercetin glycosides; acquisition of the ability to produce patuletin; and an elaboration of glycosylation patterns of patuletin.     

A CYTOGENETIC ANALYSIS OF CERTAIN POLYPLOIDS IN GRINDELIA (COMPOSITAE)

Two diploid taxa, Grindelia procera and G. camporum, and 3 tetraploid ones, G. camporum, G. hirsutula, and G. stricta, have been studied to ascertain their interrelationships. Meiosis in diploid parental strains was regular, the common chromosome configuration being 5 rod bivalents and 1 ring bivalent. The average chiasmata frequency per chromosome was 0.60. Pollen fertility was about 90% in all strains examined. Diploid interspecific hybrids had normal meiosis with an average chiasmata frequency of 0.56 per chromosome. No heterozygosity for inversions or interchanges was detected, and pollen fertility was above 85%. Meiosis in parental tetraploid strains was characterized by the presence of quadrivalents in addition to a complementary number of bivalents. The average chiasmata frequency per chromosome was 0.59 and pollen fertility was generally about 80%. Tetraploid interspecific hybrids also had quadrivalents, normal meiosis, and high pollen fertility. Close genetic relationships between the diploids and between the tetraploids are indicated, and geographical, ecological, and seasonal barriers to gene exchange exist. Attempts to obtain hybrids between diploids and tetraploids were successful in a few cases. The hybrids were tetraploid and had normal meiosis and fertility similar to parental and F₁ tetraploids. Their origin was by the union of unreduced gametes of the diploid female parent and normal pollen from the tetraploid parent. On the basis of chromosome homology, normal meiosis, plus high fertility exhibited in the diploid, tetraploid, and diploid X tetraploid interspecific hybrids, these species of Grindelia are considered to be a part of an autopolyploid complex. Gene exchange between diploids and diploids, tetraploids and tetraploids, and diploids and tetraploids is possible. Tetraploid G. camporum may have originated by hybridization between G. procera and diploid G. camporum with subsequent doubling of chromosomes and selection for the combined characteristics of the diploids.     

POLLINATION ECOLOGY OF PYRRHOPAPPUS CAROLINIANUS (COMPOSITAE)

Pyrrhopappus carolinianus and Hemihalictus lustrans constitute a mutualistic association: the early morning flowering of Pyrrhopappus provides the matinal bee with a nearly exclusive pollen source, although other plants must be visited for nectar. Female Hemihalictus, the primary pollen vector, tear open the anthers and remove the pollen before it is available to other bees. The foraging behavior of the bee insures cross-pollination. The flight pattern of the bees generally restricts the pollen dispersal range. If cross-pollination fails, then autogamy results from twisting of the styles that brings the stigmas in contact with the pollen presented on the styles of other florets. Schinia mitis is an important predator of the capitulae of P. carolinianus.     

THE GENUS PEGOLETTIA (COMPOSITAE, INULEAE)

Abstract— The genus Pegolettia (Compositae, Inuleae) from Africa, Arabia, and the Middle East is revised. The nine recognized species, viz. P. lanceolata Harv., P. baccaridifolia Less., P. gariepina A. Anderb., P. oxyodonta DC., P. retrofracta (Thunb.) Kies, P. tenuifolia Bolus, P. plumosa M. D. Hend., P. pinnatilobata (Klatt) O. Hoffm. ex Dinter, and P. senegalensis Cass., are treated cladistically, and a cladogram is presented. The species are illustrated, and their distributions mapped. Hypotheses on the mode of speciation and the biogeography of the group including a model of area relationships in southern Africa are presented.     

异裂菊属两新种

异裂菊属两新种梁健英（广西植物研究所,桂林５４１００６）关键词菊科;异裂菊属;新种ＴＷＯＮＥＷＳＰＥＣＩＥＳＯＦＨＥＴＥＲＯＰＬＥＸＩＳＣＨＡＮＧ（ＣＯＭＰＯＳＩＴＡＥ）￥ＬｉａｎｇＪｉａｎｇｙｉｎｇ（ＧｕａｎｇｘｉＩｎｓｔｉｔｕｔｅｏｆＢｏｔａｎｙ...     

FLAVONOID CHEMISTRY AND SYSTEMATICS OF TITHONIA (COMPOSITAE)

Twenty-four flavonoid compounds, including chalcones and aurones, are reported from 13 taxa of Tithonia. Pedunculin (4′, 6, 7-trimethoxy, 5, 8-dihydroxyflavone), also is characterized. The distribution of these compounds is compared to the existing classification of the genus based primarily on morphological data. By comparison with the previously proposed phylogeny of the genus, the evolution of the flavonoid system may be elucidated. It is proposed that the ancestral stock of Tithonia had flavonols, di- and tri-methoxyflavones, and 6-methoxyflavones. From this ancestral stock, a number of trends have occured in derivative taxa. These trends are: 1) a maintenance of a diversity of compounds in several evolutionary lines, 2) a reduction in the number of methoxyl substitutions, and 3) the elaboration of 5-deoxyflavones and flavonols.     

MALE GAMETOPHYTE SELECTION IN A NATURAL POPULATION OF HAPLOPAPPUS GRACILIS (COMPOSITAE)

Distributions of two forms of the A chromosome of Haplopappus gracilis in a hybrid natural population and in artificial crosses are analyzed. Pollen bearing the standard type A chromosome is generally superior to that bearing the Mexican type A when they compete on homozygous pistils of either type, but there is no selection on heterozygous pistils. The distribution of sporophyte karyotypes in the natural population is not in equilibrium, and it is surmised that the standard type A chromosome is increasing in frequency in the population.     

菊科亚菊属川甘亚菊类群订正

本文对作者本人在1983年《中国植物志》第76卷第一分册12l页上针对川甘亚菊处理过宽的问题,重新作出了订正。本文确认川甘亚菊、灰叶亚菊、深裂亚菊及下白亚菊分别为不同的种,并作出了这四个种的分种检索表。     

A QUANTITATIVE CYTOGENETIC ANALYSIS OF AN INTERSECTIONAL HYBRID IN HELIANTHUS (COMPOSITAE)

From numerous pollinations of Helianthus laciniatus A. Gray sect. Ciliares by H. annuus L. sect. Helianthus (each with n = 17), a single hybrid was grown to maturity. The hybrid was vigorous but only 2.24% pollen-fertile compared to greater than 96% fertility in the parents. Backcrossing to the parental species was unsuccessful, so the possibility of gene flow between the species in nature is remote. Chromosome pairing in the parental plants was normal, but the hybrid was heterozygous for at least one paracentric inversion and numerous translocations. Chiasma frequencies of the parental genotypes were significantly different. The hybrid was significantly different from H. laciniatus and from the midparent value but not from H. annuus. These differences in chiasma frequencies were tested by the way chiasmata were allocated among the different meiotic configurations. Methods of converting multivalents to bivalent equivalents for comparison of chiasmata distribution among species and hybrids are demonstrated.     

菊科植物的系统分类与区系地理的初步探讨

本文论述了菊科系统分类与区系地理特点。作者将菊科区分为二亚科、5超族、12族,同时将菊科世界区系分4大区、27亚区加以讨论。     

THE ORIGIN AND RELATIONSHIPS OF LASTHENIA BURKEI (COMPOSITAE)

Lasthenia burkei (Compositae) is a narrowly restricted California endemic closely related to L. conjugens and L. fremontii. These three species differ from each other by pappus and phyllary characters and in geographical distribution. All are freely intercrossable, but L. fremontii forms rather sterile artificial hybrids with its two relatives which, in turn, form fairly fertile artificial hybrids with each other. Lasthenia burkei and L. conjugens have homologous chromosomes, four of which are homologous with four of those of L. fremontii. The remaining two chromosomes probably have reciprocal translocations which lead to multivalent formation during meiosis in interspecific hybrids. Pollen viability is restored in most F₂ generations, suggesting a close genetic relationship among the three species. The evolutionary relationship among these species may be a linear one with L. burkei occupying an intermediate position between L. fremontii and L. conjugens, although the direction of this linear phylogeny is not certain, or it may be one in which L. burkei has been derived from hybridization between its two relatives. Support for the latter hypothesis comes from the appearance of some individuals in F₁ progenies of L. conjugens × L. fremontii that are morphologically indistinguishable from L. burkei (although fairly sterile). The apparently rather simple genetic basis for the morphological characteristics of each of the species in this trio suggests that the morphologically heterogeneous genus Lasthenia may be considerably more homogeneous genetically than might be suspected. Because of the diverse kinds of relationships among these three Lasthenias, possible alternative taxonomies for the group are dependent upon those relationships that a taxonomist wishes to communicate. Nevertheless, the patterns of diversification in this group have led to reaffirmation of an earlier decision that three species should be recognized.     

A NEW SPECIES OF COREOCARPUS (COMPOSITAE: HELIANTHEAE) FROM SAN PEDRO NOLASCO ISLAND,MEXICO

A new species of Coreocarpus endemic to San Pedro Nolasco Island, Mexico, C. sanpedroensis , is described and illustrated.