Protonemal and sporeling ontogeny of Leucobryum glaucum (Hedw.) Angstr.
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Accession number;00A0795870
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| Title;Protonemal and sporeling ontogeny of Leucobryum glaucum (Hedw.) Angstr. |
| Author;
BARTHOLOMEW-BEGAN S E
(West Chester Univ., Pa, Usa)
JONES N L
(West Chester Univ., Pa, Usa)
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Journal Title;J Hattori Bot Lab
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Journal Code:Y0255A
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ISSN:0073-0912
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VOL.;NO.88;PAGE.179-190(2000)
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| Figure&Table&Reference;FIG.33, REF.13 |
| Pub. Country;Japan |
| Language;English |
| Abstract;Leucobryum glaucum (Hedw.) Angstr. protonemata and sporelings were studied in order to determine and describe fundamental ontogenetic patterns. Spores were cultured under controlled, axenic conditions and developmental stages were examined using light microscopy techniques that allowed observations in multiple optical planes. Germination is exosporic, followed by a distinct developmental sequence that constructs the basal protonemal assemblage of chloronemal filaments. Extensive branching from side branch initials and transformations of filament types yield a mature, heterotrichous protonema composed of prostrate chloronema and caulonema, a monopodial system of erect chloronemal branches, and thigmotropic rhizoids. Target cells, which form on filaments that are intermediate in type between chloronema and caulonema or on distinct caulonemal filaments undergo a specific, uniform pattern of sporeling ontogeny which is characterized by the production of an apical initial with three cutting faces that segments briefly, then is transformed into an adult obovoidal apical cell. Repeated adult segmentation and merophyte development result in a juvenile L. glaucum gametophyte. Traditionally, Leucobryum sporelings have been classified as representatives of the Bryum type. However, the detailed ontogenetic patterns of L. glaucum protonemata and sporelings reveal characters that not only define Bryum type sporelings, but also Funaria type sporelings. This suggests that more emphasis be placed on the fundamental ontogenetic patterns of protonemata and sporelings as criteria for classifying basic moss sporeling types. (author abst.) |
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