Form and Biotype Formation in Calamagrostis Purpurea

Nygren, Axel

doi:10.1111/j.1601-5223.1951.tb02908.x

Cited by 29 publications

(6 citation statements)

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“…alpina ssp. alpina in northern Scandinavia may therefore be reminiscent of that met with in, for example, some groups of the genera Culamagrostis and Poa (see NYGREN 1946NYGREN , 1950NYGREN , 1951LOVE 1952;MUNTZING 1954 for surveys and further references). In spite of the great amount of information available on chromosome numbers in these genera, our knowledge of chromosome morphology is, however, very scant as far as I can judge.…”

Section: Evolution and Phytogeographymentioning

confidence: 79%

Karyotypes and population structure in aneuploid Hierochloë alpina ssp. alpina (Gramineae) in northern Scandinavia

Weimarck

2009

Hereditas

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The chromosome numbers of 65 plants of Hierochloë alpina (Willd.) Roemer and Schultes ssp. alpina from 12 populations ranged from 64 to 78. Thirteen different karyotypes were represented. Most chromosomes were metacentric, but subtelocentric and telocentric markers occurred in some populations. Phenotypic variation in chromatographically obtained spot patterns was found. Apomixis previously found in the taxon is presumed to be facultative. H. alpina ssp. alpina from other parts of the area of distribution than northern Scandinavia is not known to be cytologically variable to this extent, nor are other taxa of Hierochloë. The origin and geographic distribution of cytologic aberrancy and its possible evolutionary and phytogeographical implications are discussed.

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Section: Evolution and Phytogeographymentioning

confidence: 79%

Karyotypes and population structure in aneuploid Hierochloë alpina ssp. alpina (Gramineae) in northern Scandinavia

Weimarck

2009

Hereditas

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“…Where this has been studied, percentage sexual ES formation was highest when plants were grown in suboptimal conditions (as in cyclically apomictic animals). Examples include facultative apomicts of i ) Boechera , where sexual ES formation was most frequent in stressed inflorescences [ 34 ], ii ) Calamagrostis Adans., where sexual ES formation was most frequent in early-forming spikelets [ 35 ], iii ) Ageratina Spach [ 36 ] and Limonium Mill. [ 37 ], where sexual ES formation was most frequent in plants exposed to cold stress, iv ) Dichanthium Willem.…”

Section: Discussionmentioning

confidence: 99%

Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules

et al. 2011

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BackgroundGenetically unreduced (2n) embryo sacs (ES) form in ovules of gametophytic apomicts, the 2n eggs of which develop into embryos parthenogenetically. In many apomicts, 2n ES form precociously during ovule development. Whether meiosis and sexual ES formation also occur precociously in facultative apomicts (capable of apomictic and sexual reproduction) has not been studied. We determined onset timing of meiosis and sexual ES formation for 569 Sorghum bicolor genotypes, many of which produced 2n ES facultatively.ResultsGenotype differences for onset timing of meiosis and sexual ES formation, relative to ovule development, were highly significant. A major source of variation in timing of sexual germline development was presence or absence of apomictic ES, which formed from nucellar cells (apospory) in some genotypes. Genotypes that produced these aposporous ES underwent meiosis and sexual ES formation precociously. Aposporous ES formation was most prevalent in subsp. verticilliflorum and in breeding lines of subsp. bicolor. It was uncommon in land races.ConclusionsThe present study adds meiosis and sexual ES formation to floral induction, apomictic ES formation, and parthenogenesis as processes observed to occur precociously in apomictic plants. The temporally diverse nature of these events suggests that an epigenetic memory of the plants' apomixis status exists throughout its life cycle, which triggers, during multiple life cycle phases, temporally distinct processes that accelerate reproduction.

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“…This morphology has not been well-studied, causing various interpretations by taxonomists when they try to separate species. Some studies have determined that morphological variation is due to apomixis and polyploidy (Nygren, 1946(Nygren, , 1948(Nygren, , 1949(Nygren, , 1951(Nygren, , 1954a(Nygren, , 1954b(Nygren, , 1958(Nygren, , 1962Stebbins, 1941;Tateoka, Hiraoka and Tateoka, 1977).…”

Section: Morphologymentioning

confidence: 99%

Systematics of Calamagrostis section Deyeuxia, subsection Stylagrostis, (Poaceae: Pooideae)

Escalona

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treatment for 14 species, hoping it will help clarify the taxonomy of Calanagrostis. However, more basic research is needed and future work will continue in order to improve understanding of the taxonomic position of the South American species. 4 II. MATERIALS AND METHODS A. Herbarium Studies Data obtained from herbarium specimens included morphological measurements, observations, and distributions reported by collectors, as well as common names that have been applied to the plants. Specialized collections were borrowed from various herbaria, cited according to Holmgren, Keuken, and Schofield (1981).

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Form and Biotype Formation in Calamagrostis Purpurea

Cited by 29 publications

References 4 publications

Karyotypes and population structure in aneuploid Hierochloë alpina ssp. alpina (Gramineae) in northern Scandinavia

Karyotypes and population structure in aneuploid Hierochloë alpina ssp. alpina (Gramineae) in northern Scandinavia

Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules

Systematics of Calamagrostis section Deyeuxia, subsection Stylagrostis, (Poaceae: Pooideae)

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