TRIBAL PLACEMENT OF MARSHALLIA (ASTERACEAE) USING CHLOROPLAST DNA RESTRICTION SITE MAPPING

The examination of morphological traits has failed to resolve the tribal placement of Marshallia. Suggested relationships for this anomalous genus have, at various times, included Eupatorieae, Heliantheae, Vemonieae, and Inuleae. Chloroplast DNA restriction site mapping, using Bamadesiinae (Mutisieae) as the outgroup, revealed 981 restriction site mutations, 332 of which were phylogenetically informative, for 60 genera representing 15 tribes of Asteraceae. Wagner parsimony produced 36 equally parsimonious tress of 729 steps, and Dollo parsimony produced 34 equally parsimonious trees of 759 steps. Monophyletic groups, resulting from the Wagner analysis, were further tested with the bootstrap method. The placement of Marshallia in the Heliantheae-Tageteae-Coreopsideae-Eupatorieae complex was consistent for all trees produced. Tageteae and Coreopsideae form the sister group to paraphyletic Heliantheae, with Marshallia sharing its most recent common ancestor with Galinsoga, Palafoxia, and Bahia. The Eupatorieae form a monophyletic clade that is derived from helianthoid ancestors.     

THE HYBRID ORIGIN OF ASTER ASCENDENS (ASTERACEAE)

Aster ascendens Lindl. is a rhizomatous perennial of the Great Basin region of the western United States, with a chromosome base number of x = 13. Populations in the southern and western parts of the range are mainly diploid (n = 13) and those in the north and east are mainly tetraploid (n = 26). This species is postulated to be an amphiploid which has resulted from hybridization between the western Cordilleran A. occidentalis (T. & G.) Hook, and the Great Plains species A. falcatus Lindl. Aster ascendens is intermediate between these two species in most morphological traits, but resembles A. occidentalis in ray color and general growth habit, and A. falcatus in the shape of the outer phyllaries. The karyotype of A. ascendens also exhibits a combination of the features found in A. occidentalis and A. falcatus karyotypes. Of the specimens collected for this study, 13% were putative backcrosses of A. ascendens to one of its parent taxa or to a closely related species; this suggests that there is potentially continuing genetic interchange between the species groups that gave rise to A. ascendens.     

COMPARATIVE MORPHOLOGY OF THE CAPITULUM OF ENCELIOPSIS (ASTERACEAE: HELIANTHEAE)

Features of the capitula of all four species of Enceliopsis were examined with light and scanning electron microscopy, measured, and subjected to univariate analysis. Differences were found in the complement, distribution, and density of trichomes, the size of the receptacle, ray ligule, and disk corolla tube, and the size and shape of the phyllaries, paleae, disk corolla throats, and achenes. Morphology of trichomes, phyllaries, and achenes, as well as other vegetative characteristics, show that E. nudicaulis, E. covillei and E. argophylla form a group separate from E. nutans. Features of the achene suggest affinity of the former group with Geraea, whereas features of the trichomes and achene of E. nutans support affinity with Encelia. Characters of the receptacle, paleae, ray and disk corollas, and achene clearly show that E. nudicaulis, E. covillei, and E. argophylla are distinct.     

THE ROLES OF PLANT HORMONES IN THE GROWTH OF THE COROLLA OF GAILLARDIA GRANDIFLORA (ASTERACEAE) RAY FLOWERS

Corolla elongation and the roles of plant hormones in this process in Gaillardia grandiflora Van Houtte ray flowers were examined. The sterile ray flowers elongated during a 2-day period, and corolla growth was accompanied by fresh and dry weight increases and epidermal cell elongation (greatest near the base of the corolla) but not by cell division. Corollas excised from young ray flowers were measured during treatment in vitro with solutions of plant growth regulators. They elongated in response to gibberellins and fusicoccin but did not respond to auxins, cytokinins, abscisic acid, ethylene, or inhibitors of ethylene biosynthesis. Sequential and simultaneous hormone applications indicated no additive or synergistic effects between hormones, but auxin did reduce gibberellin-promoted growth. Analyses of endogenous auxins showed no significant variation, and ethylene production decreased prior to elongation, while a 20-fold increase in endogenous gibberellin activity was observed just prior to rapid corolla elongation. It appears that corolla growth in Gaillardia is accomplished by an increase in gibberellin activity alone, that multiple hormone interactions are not important in the control of corolla growth, and that part of the mode of action of gibberellin is acid-induced growth.     

华夏鱼科(Huashiidae)的系统关系及分类学意义

本文用 Hennig 86 软件对华夏鱼类的系统关系进行了重新探讨,认为目前将华夏鱼类归入骨舌鱼超目是由于简约性的缘故.同时,本文对简约原则的适用性进行了讨论.     

THE AMINO ACIDS OF EXTRAFLORAL NECTAR FROM HELIANTHELLA QUINQUENERVIS (ASTERACEAE)

The extrafloral nectar from involucral bracts of Helianthella quinquenervis has more nonprotein (5) and total (24) amino acids than have been reported for any other extrafloral nectar. Seven to twelve additional unknowns, probably nonprotein amino acids, were also found. The concentrations of amino acids (8–10 on the histidine scale) were the highest ever reported for extrafloral nectar. Most amino acids were found in all samples, while others were variable in their occurrence.     

COMPARATIVE ANATOMY OF SOME PARENTS AND HYBRIDS OF THE HAWAIIAN MADIINAE (ASTERACEAE)

Comparative leaf morphology and anatomy was examined in five species and four hybrids involving three genera of Hawaiian Madiinae (Asteraceae). The comparisons included Argyroxiphium grayanum, Dubautia ciliolata subsp. ciliolata, D. knudsenii subsp. knudsenii, D. scabra subsp. leiophylla, D. scabra subsp. scabra, and Wilkesia gymnoxiphium, and the hybrids A. grayanum × D. scabra subsp. leiophylla, D. ciliolata subsp. ciliolata × D. scabra subsp. scabra, D. knudsenii subsp. knudsenii × D. scabra subsp. leiophylla, and W. gymnoxiphium × D. scabra subsp. leiophylla. Foliar morphology, leaf tissue organization, and various characters of stomata and trichomes were compared, using epidermal peels, cross and paradermal sections, and clearings of leaves. Pronounced anatomical differences among these closely related taxa were characterized, and effects of hybridization on the expression of anatomical features were documented. Most comparisons of parents and hybrids revealed statistically significant differences in leaf size, distribution of adaxial and abaxial stomata, and marginal and surface trichomes. In most instances hybrids demonstrated intermediate status in their foliar characters, indicating that these features are inherited from both parents. However, differences in foliar characters were usually of sufficient magnitude to allow recognition of hybrids as well as parents.     

DISPERSION OF SEEDLINGS OF THE PRAIRIE COMPASS PLANT,SILPHIUM LACINIATUM (ASTERACEAE)

Although the dispersal of seeds around individual plants (the seed shadow) has frequently been characterized, the dispersion of seedlings around plants (the seedling shadow) has rarely been examined. We mapped 101 and 149 seedlings of the prairie compass plant (Silphium laciniatum) that appeared in our study area in 1987 and 1990 following mass flowering in 1986 and 1989. We also mapped the locations of flowering stems which appeared in 1986 and 1989 and recorded the number of flowerheads at each stem location. The frequency distributions of distance between a seedling and the nearest flowering stem were identical in the 2 years, with a median distance of 1.0 m. The large size and lack of wind-dispersal structures of compass plant seeds (achenes) are responsible for their limited dispersal. From estimates of the total seed production in the study area in 1986 and 1989, we calculated that about 1% of seeds became seedlings in each year. Flowering stem locations with a higher number of flowerheads had a significantly higher density of seedlings around them. This indicates that recruitment to compass plant populations is not a “lottery”; individual plants that produce more seeds produce, on average, more seedlings.     

缘蝽科族级单元系统发育关系支序分析(半翅目:异翅亚目:缘蝽总科)

在已有比较形态学研究基础上,本文选择了15个特征方面（外生殖器为主）的74个新征,以支序分析方法探讨了缘蝽科族（或亚科）的系统发育关系。结果表明棒缘蝽亚科、希缘蝽族、沟缘蝽族较为原始,与其余类群差异较大,缘蝽科的范围值得进一步研究;除Chariesterini外的缘蝽亚科是高等的缘蝽类群;Chariesterini似应从缘蝽亚科中独立出来;狭义巨缘蝽族以及萧的鼻缘蝽族、梭缘蝽族、昧缘蝽族、曼缘蝽族成立;拟黛缘蝽属、副黛缘蝽属、华黛缘蝽属、异黛缘蝽属应从”黛缘蝽族”中分别独立出来成立新族,即拟黛缘蝽族、副黛缘蝽族、华黛缘蝽族和异黛缘蝽族,以使原有的黛缘蝽族成为自然类群。     

A GENERIC CONSPECTUS OF THE SUBTRIBE PERITYLINAE (ASTERACEAE-HELENIEAE) AND REASSESSMENT OF ITS TRIBAL POSITION

The subtribe Peritylinae, long treated as an element of the polyphyletic, chaffless tribe Helenieae, is recognized as containing 7 or 8 genera (Perityle, Pericome, Correllia, Amauria, Eutetras, Oxypappus, Eatonella and possibly Hulsea). Using mainly morphological data and a phyletic perspective, we concluded that the Peritylinae is best treated as a subtribe within the Senecioneae, where it should be positioned with or near Crocidium and Bartlettia. Reasons for this disposition are discussed in some detail.     

DISTRIBUTION OF KRANZ SYNDROME AMONG ASTERACEAE

A broad survey of the Asteraceae, involving visual characters, was undertaken to ascertain the occurrence of possible Kranz-type (C₄) plants. One hundred and seven taxa representing 51 genera were examined by mass spectrometry for their ¹³C/¹²C ratios in dried leaf tissue. Species possessing the high ¹³C/¹²C ratio typical of the Kranz syndrome were found in genera belonging to the following tribes: Heliantheae (subtribe Coreopsideae)—Chrysanthellum (4 spp.), Eryngiophyllum (1 sp.), Glossocardia (1 sp.), Glossogyne (1 sp.), Isostigma (5 spp.); Tageteae—Pectis (21 spp.); and Helenieae—Flaveria (4 spp.). The only genus to possess both C₃ and C₄ species was Flaveria in which all but four species appear to possess a C₃-type metabolism. When appropriate, the phyletic input of these data is discussed.     

THE GEOGRAPHICAL DISTRIBUTION OF B-CHROMOSOMES OF XANTHISMA TEXANUM DC. (ASTERACEAE). I. SURVEY OF THE RANGE

The distribution of B-chromosomes throughout the range of Xanthisma texanum has been determined from approximately 750 individuals from 80 wild populations in Texas, Oklahoma, and New Mexico. Counts of meiotic chromosome figures of n = 4_II + 1 B_I and n = 5_II (4_II + IB_II) are reported for the first time for subsp. texanum var. texanum and for subsp. texanum var. orientalis. The wide occurrence of B-chromosomes in natural populations of subsp. drummondii is also documented. B-chromosomes are present in 22 (27.2%) randomly distributed populations whose characteristics are in no way distinct from populations without B-chromosomes. In populations with B-chromosomes present, 19.8% of the plants contained one or two B-chromosomes, but in total only 5.8 % of all plants contained one or two B-chromosomes. All populations in one isolated population group of subsp. drummondii lack B-chromosomes.