Skip to main navigation menu Skip to main content Skip to site footer

Taxonomic Implication of Conducting Elements in the Acrocarpous Mosses

Abstract

Present study deals with the structure and development of conducting elements in the nine orders of acrocarpous mosses. The significance of conducting tissues in mosses in relation to their habitat conditions, growth forms and leaf cell patterns has been discussed. Features of cells in different portions of the stem and the laminal cell patterns and costa are taken into consideration. Although water-conducting cells are unspecialized in mosses, yet the study shows that they seem to play a vital role in the conduction and provide additional criteria for the distinction of taxa. Four categories have been determined as (i) Acrocarpous mosses with a distinct thick-walled conducting strand (6-7 layered) as hydrome which is surrounded by patches of leptoids. Cortex consists of thick walled cells (6-10 layered). Costa has stereidal cells and well developed conducting elements in leaf, example Polytrichum (ii) Acrocarps with thick-walled, narrow, elongated conducting strand (4-5 layered), cells angular in the cortex (6-8 layered). Leaf cells are rectangular, irregular and porous with incrassate walls, example Dicranum (iii) Acrocarps with conducting tissue (2-5 layered) stereidal, thick walled or thin walled varying in the course of development. Leaf cells are mutipapillate, rounded-quadrate, costa is present, examples Hyophila, Philonotis and (iv) Epiphytic pleurocarps with conducting cells rudimentary, thickened, scattered (2-4 layers) and parenchymatous, cortical cells (2-3 layered) thick walled. Leaf cells are small, rounded or linear and papillate, costa may be present or absent, example Leucodon. The study would constitute a formidable task, especially if intraspecific structural variability is considered. It serves a model system in the eco-physiological aspects.

Keywords

Ectohydric, Endohydric, External Conduction, Leaf Cell Pattern, Stereidal Cells.

PDF

Downloads

Download data is not yet available.

References

  1. Buch, H. 1947. Ueber die Wasser-und Mineralstoffversorgungder Mosse (Part-2). Soc. Science Fenn Commemor. Biol. 9(20): 1-61.
  2. Hebant, C. 1970. A new look at the conducting tissues of mosses (Bryopsida): their structure, distribution and significance. Phytomorphology 20:390-410.
  3. Hebant, C. 1974. Studies on the development of the conducting tissue-system in the gametophytes of some Polytrichales. II. Development and structure at maturity of the hydroids of the central stand. J. Hattori Bot. Lab. 38: 565-607.
  4. Hebant, C. 1977. The conducting tissues of Bryophytes. J. Cramer. Lehre. Germany. 157.
  5. Hebant, C. 1979. Conducting Tissues in Bryophyte Systematics. In: G.C.S. Clarke & J.G. Duckett (eds.). Bryophyte Systematics. 365-383. Academic Press. London.
  6. Kawai , I. 1991. Systematic studies on the conducting tissue of the gametophyte in musci (18). On the relationship between the stem and the rhizome. Annual Report of Botanical Garden. Fascicle Sciene Kanazawa University 14:17-25.
  7. Proctor. M.C.F. 1979. Structure and eco-physiological adaptation in bryophytes. In: G.C.S. Clarke & J.G. Duckett. (eds.). Bryophyte Systematics. 479-509. Academic Press. London.
  8. Proctor, M.C.F. 2000. Mosses and alternative adaptation to life on land. New Phytologist 148:1-6.
  9. Taylor, T.N. 1988. The origin of land plants: Some answers, more questions. Taxon 37:805-833.
  10. Zamski, E. and S. Trachtenberg. 1976. Water movement through hydroids of a moss gametophyte. Israel J. Bot. 25:168-173.