+ Translate

Extensible helical wall thickenings of the testa of chiloschista lunifera orchidaceae as seed attachment mechanisms

, : Extensible helical wall thickenings of the testa of chiloschista lunifera orchidaceae as seed attachment mechanisms. Berichte der Deutschen Botanischen Gesellschaft 93(2): 391-404

The seed coat micromorphology of the tropical Asian epiphytic orchid C. lunifera (Rchb. f.) J.J. Smith is described, and illustrated by SEM micrographs. The spherical embryo is covered by a 0.6 mm long seed coat of thin-walled, dead cells. The testa exhibits a microstructure characteristic of the subtribe Sarcanthinae. At the micropylar end of the seed the testa is composed of 2 different cell types, both characterized by secondary helical wall thickenings. One cell type (E-cells) is identifiable by a thick banded helix; these tracheoid cells resemble tracheal elements in vascular tissue. The 2nd cell type (F-cells) is characterized by thinner walls and a very fine thread like wall helix. After wetting the seed with water, within a few seconds the E-cells extend slightly and show an active hygroscopic movement. The F-cells swell and the thin helical wall thickenings become unravelled, producing threads up to 4 mm long. This positive mechanism enables the seed of the epiphyte to attach to a suitable substrate such as moist bark. From .apprx. 1100 spp. in 210 orchidaceous genera studied, C. lunifera is the only taxon to have this special type of dispersal mechanism. This is the only known example within the Monocotyledons of an attachment mechanism operated by means of hygroscopic movement and unravelling of helical wall thickenings. Comparison with similar mechanisms in certain Dicotyledons (Cobaea, Blepharis) indicate that the mechanism of Chiloschista could be among the most complicated attachment mechanisms in Angiosperms.

(PDF 0-2 workdays service)

Accession: 005432775

Submit PDF Full Text: Here

Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:

Related references

Barthlott, W.Z.egler, B., 1980: On extensible helical wall thickening of the testa of Chiloschista lunifera (Orchidaceae) as seed attachment mechanisms. Berichte der Deutschen Botanischen Gesellschaft 93(2): 391-403

Misra, S., 1986: Notes on Chiloschista lunifera (Reichb. f.) J.J. Sm. from Orissa. Biology conservation and culture of orchids: papers presented at a national seminar organized by The Orchid Society of India held at Panjab University 3-4 April 1985 editor SP Vij: 318

Schmid R.; Baas P., 1984: The occurrence of scalariform perforation plates and helical vessel wall thickenings in wood of myrtaceae. The occurrence of multiple perforation plates and helical wall thickenings in vessel elements of 144 spp. (plus 12 varieties and 2 hybrids) in 53 genera of Myrtaceae was extensively explored. Scalariform perforation plates occur in 40 spp. (plus 1...

Leroux, O.; Bagniewska-Zadworna, A.; Rambe, S.K.; Knox, J.P.; Marcus, S.E.; Bellefroid, E.; Stubbe, D.; Chabbert, B.; Habrant, A.; Claeys, M.; Viane, R.L.L., 2011: Non-lignified helical cell wall thickenings in root cortical cells of Aspleniaceae (Polypodiales): histology and taxonomical significance. Extraxylary helical cell wall thickenings in vascular plants are not well documented, except for those in orchid velamen tissues which have been studied extensively. Reports on their occurrence in ferns exist, but detailed information is missing....

Timell, T.E., 1978: Helical thickenings and helical cavities in normal and compression woods of Taxus baccata. EM studies of normal and compression sapwood from a single tree of Taxus baccata showed that longitudinal tracheids of compression wood contained helical thickenings (similar to those of normal wood) but not helical cavities. The thickenings were...

Thompson, D.I.; Edwards, T.J.; Staden, J. van, 2001: In vitro germination of several South African summer rainfall Disa (Orchidaceae) species: is seed testa structure a function of habitat and a determinant of germinability?. Seed germination is consistently poor for the majority of Disa species, with in vitro culture revealing a decrease in species germinability as one moves from the winter to the summer-rainfall areas of South Africa. In an effort to enhance seed cul...

Freudenstein J.V., 1991: A systematic study of endothecial thickenings in the orchidaceae. Endothecial cell thickenings were examined in anther macerations of representative species from 210 genera of the Orchidaceae. Nearly all species examined possessed the characteristic thickened walls which, in several tested species, gave a positi...

Ohtani, J.; Meylan, B.A.; Butterfield, B.G., 1984: A note on vestures on helical thickenings. The helical thickenings of vessel elements were studied in: Carmichaelia angustata, C. arborea, C. flagelliformis, C. grandiflora, C. rivulata, Chordospartium stevensonii, Corallospartium crassicaule, Notospartium carmichaeliae, Sophora microphyll...

Meylan, B.A.; Butterfield, B.G., 1978: Occurrence of helical thickenings in the vessels of new zealand woods. Helical thickenings were observed on the vessel walls of 90 woods indigenous to New Zealand. They were not observed in a further 88 spp. Four types of thickenings are described: faint striations, light helical thickenings sometimes merging with th...

Yoshizawa N.; Itoh T.; Shimaji K., 1985: Helical thickenings in normal and compression wood of some softwoods. Compression wood in some softwoods with helical thickenings on the inner surface of normal wood tracheids were examined using scanning EM. Helical thickenings of Taxus, Torreya and Cephalotaxus have narrow bases, and are loosely attached to the in...