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Browsing by Author "Castroviejo, Santiago"

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  • Holcus azoricus M. Seq. & Castrov. (Poaceae), a new species from the Azores Islands
    Publication . Sequeira, Miguel Menezes de; Castroviejo, Santiago
    A new species of Holcus L. (Poaceae), endemic to the Azores archipelago (Portugal), is described. The vegetative and reproductive structures were studied. The diagnostic characters were compared with those of closely related species. New chromosome counts in Holcus azoricus M. Seq. & Castrov. (2n = 35) and H. rigidus Hochst. (2n = 28) are included. A possible hybrid origin is hypothesized; the potential parents are H. lanatus L. and H. rigidus.
    2007Journal article Open access Show more
  • Holcus pintodasilvae (Poaceae, Pooideae, Poeae), a new species from the Island of Madeira (Portugal), and notes on Macaronesian Holcus
    Publication . Sequeira, Miguel Menezes de; Castroviejo, Santiago
    A new species of Holcus L. (Poaceae), endemic to the island of Madeira (Portugal), is here described as H. pintodasilvae M. Seq. & Castrov. This new species is morphologically closely related to the Macaronesian endemics H. rigidus Hochst. ex Hochst. (Azores Archipelago) and H. mollis L. subsp. hierrensis Stierst. (El Hierro Island, in the Canary Islands) but differs by having the culm nodes light brown, the leaves with a glabrous sheath and subspreading lamina attenuated to an acuminate apex, the glumes blunt, shiny, glabrous (except in the minutely scabrous veins), the upper glume with proximal lateral veins, and the lemma of the upper floret with an awn ca. 4 mm, twice as long as the lemma. Chromosome counts in H. pintodasilvae are tetraploid (2 n = 28). Morphology, ecology, biogeog raphy, and conservation issues are discussed and related to other Macaronesian Holcus taxa. Holcus (totaling less than 20 individuals), and its IUCN conservation status is Critically Endangered (CR). A new specific status is proposed for H. mollis subsp. hierrensis, as H. hierrensis (Stierst.) Stierst. & M. Seq., based on its chromosome number and morphological identity.
    2013Journal article Open access Show more