Cytogenetic Evidence Supporting the Merger of Heterotheca and Chrysopsis (Compositae)

Harms, Vernon L.

doi:10.2307/2805387

Cited by 12 publications

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“…) have demonstrated a comparable situation for Chrysopsis (n = 4, 5, 9), which they consider to be more closely related to Bradburia (x = 3) and Xanthisma (x = 4), than to Heterotheca and Pityopsis (x = 9), with which the genus has been allied by other workers (cf. Harms, 1965Harms, , 1974a. A similar allotetraploid origin of n (or x) = 9 is suggested for some members of Haplopappus and Psilactis, for the Aster group recently segregated by Love and Love (1982) as Almutaster and, questionably, also for Noticastrum.…”

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confidence: 64%

Chromosomal Features as Generic Criteria in the Astereae

Jones

1985

TAXON

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Summary Several examples may serve to address four basic questions concerning the applicability of chromosomal features to the determination of generic limits in the Astereae: 1) What do chromosome numbers per se tell us? 2) Can we assume that x = 9 (or any other base number) is homologous for all taxa sharing the character state? 3) Can genera with more than one basic chromosome number be regarded as monophyletic? and 4) are chromosomal features correlated with gross morphological characters that will render them useful in the construction of general classifications? The evolutionary conservatism that makes chromosomal features very strong characters also limits the usefulness of the most common feature studied: the basic chromosome number. Chromosome count statistics are presented as a partial answer to the first question and, to prove a point, a “new” chromosome count is reported for Aster carolinianus. Examples are cited (e.g., Astranthium, Brachyscome, Chrysopsis, and Aster sensu lato) to show that base numbers may be primitive, or they may be derived by way of either dysploid reduction or amphidiploid increase. It is mainly with regard to the third question that concepts diverge, and there is no simple answer. The true situation may be that most genera are monobasic, but that there are a few which are not. In this connection, a well‐known example in the Aster alliance is discussed, which leads to an answer regarding the last question. Chromosomal features are basic to an understanding of relationships in the Astereae, but more so at the infrageneric than the generic level. Unless correlated with gross morphological (and/or distributional) characteristics, they are of limited value in the determination of generic boundaries.

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confidence: 64%

Chromosomal Features as Generic Criteria in the Astereae

Jones

1985

TAXON

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“…The use of achaenial pappus characteristics for generic distinction has recently been demonstrated to be an unreliable feature in other related genera in the Coreopsidineae (Harms 1965) and in the Inuleae (Wild 1964). Besides, the other character employed in support of generic distinction, viz.…”

Section: Methodsmentioning

confidence: 99%

Microlecane (Sch. Bip.) Benth.: a congener of Bidens (Compositae – Heliantheae)

Tadesse

1984

Nordic Journal of Botany

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Microlecane (Sch. Bip.) Benth.: a congener of Bidens (Compositae -Heliantheae) Mesfin Tadesse Mesfin, T. 1984. Microlecane (Sch. Bip.) Benth.: a congener of Bidens (Compositae -Heliantheae). -Nord. J. Bot. 4: 737-746. Copenhagen. ISSN 0107-055X. The systematic position of the genus Microlecane (Sch. Bip.) Benth. within the Coreopsidineae (Compositae-Heliantheae) is reviewed. It is found to be congeneric with Bidens L., and the three 'species' described for it are transferred to this genus. Microlecane abyssinica (Sch. Bip.) Benth. ex Oliv. & Hiern is Bidens setigera (Sch. Bip.) Sherff and M. occidentalis Hutch. & Dab. becomes B. occidentalis (Hutch. & Dalz.) Mesfin, comb. nov. M. carhafa Hutch., based on three syntypes, is shown to be heterogeneous. Two of the syntypes belong to Coreopsis schimperi 0. Hoffm. (non Bidens schimperi Sch. Bip.) for which the name E. carinata Cuf. ex Mesfin has recently been proposed. The third syntype of M. carinata belongs to a completely unrelated species. Brief historical notes, typifications, descriptions, notes on distributions and habitats, and distribution maps are provided.

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“…Taxonomic judgements should be made, as usual, in context with information from all available sources. Crossing data are as equivocal as any other type when it comes to evaluating whether genera should be merged or separated, especially if only two or a few species have been used to provide the data (Harms, 1965;Jackson, 1962). However, when conditions allow for a representative number of species to be utilized in the crossing experiments, the data can be as overwhelming as any other type.…”

Section: Interpretation Ofdatamentioning

confidence: 99%

“…Crossing data have been used to help determine the generic position of species whose status is questionable (Arnold and Jackson, 1978;Heiser, 1963;Smith, 1965); to help define subgeneric taxa (Arnold and Jackson, 1978;Jackson, 1979;Powell, 1972a;Rabakonandrianina and Carr, 1981); to merge genera (Clausen, 1962;Harms, 1965;Jackson, 1962;Jackson, 1979;Olorode and Torres, 1970;Powell, 1972a); to show generic relationships (Harberd and McArthur, 1980;Heiser, 1963;Kruckeberg, 1962;Kruckeberg and Hedglin, 1963;Menzel, 1962;Mitsuoka and Ehrendorfer, 1972;Powell, 1972aPowell, , 1978Rabakonandrianina and Carr, 1981;Tara, 1979); in a limited number of studies to help establish generic boundaries (Clausen, 1962;Irving et al, 1979;Kruckeberg, 1962;Pinkava, 1967;Powell, 1972aPowell, , 1978; and for yet other purposes. A strong theme to be derived from the studies cited is that artificial hybridizations are appropriate for widespread and general use in the Asteraceae as a methodological approach to the generic problem.…”

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confidence: 99%

Crossing Data as Generic Criteria in the Asteraceae

Powell

1985

TAXON

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. International Association for Plant Taxonomy (IAPT) is collaborating with JSTOR to digitize, preserve and extend access to Taxon. SummaryCrossing data have long been used to help determine the position of species whose generic status is questionable, to help define subgeneric taxa, to merge genera, and, in a limited number of studies, to help establish generic boundaries. Previous studies in the subtribes Peritylinae and Flaveriinae (Helenieae) have demonstrated that crossing data can be employed as a major approach in delimiting generic entities and in establishing relationships between genera. In fact, in the above taxa crossing data proved to be more useful at the genus level than at the species level. Such crossing tests can be employed at optimum only if it is possible to produce hybrids between most of the species in the putative genera concerned. It does appear that it is often possible to obtain comprehensive data from artificial interspecific hybridizations, especially when allopatric perennial taxa are involved. The interpretation of crossing data may present problems because variable interfertility values in different taxa are to be expected, and independent taxonomic judgements must be made in context with information from other approaches. In the tribe Eupatorieae, where extensive generic reorganization has been proposed in recent years, hybridization tests may be possible in some groups (Carterothamnus x Hofmeisteria; Koanophyllon x Pseudokyrsteniopsis) but not in others (Brickellia).If a group of species can be crossed successfully among themselves (i.e., if F, hybrids can be examined for fertility) then artificial hybridization provides a good method for the delineation of genera especially when used in context with data from other approaches. In fact, in many groups, crossing data may be more useful at the genus level than at the species level.Crossing data have been used to help determine the generic position of species whose status is questionable (Arnold and Jacksonand for yet other purposes. A strong theme to be derived from the studies cited is that artificial hybridizations are appropriate for widespread and general use in the Asteraceae as a methodological approach to the generic problem. The Peritylinae and Flaveriinae ExamplePrevious studies in the subtribes Peritylinae and Flaveriinae provide an example of how crossing data can be employed as a major approach in delimiting genera and in establishing relationships between genera (Powell, 1969(Powell, , 1972a(Powell, , 1972c(Powell, , 1973(Powell, , 1974(Powell, , 1978. In the Peritylinae, crossing data weighed heavily in the eventual recognition of three traditional genera (Pappothrix, Laphamia, Per...

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Cytogenetic Evidence Supporting the Merger of Heterotheca and Chrysopsis (Compositae)

Cited by 12 publications

References 0 publications

Chromosomal Features as Generic Criteria in the Astereae

Chromosomal Features as Generic Criteria in the Astereae

Microlecane (Sch. Bip.) Benth.: a congener of Bidens (Compositae – Heliantheae)

Crossing Data as Generic Criteria in the Asteraceae

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