Pits of a softwood (Pinus wallichiana) and a hardwood (Mallotus japonicus) were studied by Cryo-scanning electron microscopy (Cryo-SEM). The samples were chemically untreated and fully hydrated during freezing. Tori of P. wallichiana were frequently aspirated. It is not clear whether torus aspiration was caused by the freezing process or other factors during preparation. Aspirated tori had a turgid appearance. Offcenter aspirated tori which did not completely cover the pit pore could be detected. The margo strands were usually quite large and fanned out into fibrillar structures at the pit border. Pit membranes of M. japonicus had a very granular appearance. No fibrillar structures, different layers or pores could be detected. The granular structures may have developed from a continuous layer covering the pit membrane during freezing. Cryo-SEM is discussed as a further suitable tool for obtaining novel information about the native state of pit membranes. Future studies are needed to validate whether all observed features represent characteristics of the native state.
This paper examines the effects of 30 preparation techniques on SEMimages of pit membranes in vessels and tracheids from the two latest growth rings in twigs of Pinus wallichiana, Fraxinus americana and Laurus nobilis. Most variation observed is due to coating and treatment with chemical solutions, such as acetone, ethanol and hydrogen peroxide. The effects of chemicals appear to be associated with the thickness of the pit membrane, resulting in an increased density and diameter of pores in pit membranes of F. americana and L. nobilis and an almost complete dissolution of the porous margo in P. wallichiana. Although different protocols offer advantages for different species, the following methods are recommended: (1) the use of fresh material, (2) air-drying without any chemical treatment, (3) splitting of dried samples, (4) vacuum evaporation with platinum, and (5) SEM-imaging at an accelerating voltage below 5 kV.
Pradesh, India, and X. pini Ganguly, Singh, Lal & Rathour, 2008 , described from the rhizosphere of Pinuswallichiana in Bhutan. Morphometrics of both species overlap with those of X. macrodora and the presence of a filled spermatheca described and/or figured for X. pruni and X. pini suggests
. 1981 . Variation in tracheid length in Blue Pine ( Pinuswallichiana A. B. Jackson). Part2: radial pattern of variation in tracheid length in the first-formed earlywood from pith to bark . Wood Sci. Technol. 15 : 275 – 286 .
Shimakura M . 1936 . The height and number of rays in some
°40′N, 74°42′E). The vegetation is represented by moist temperate coniferous forest with sub-alpine and alpine grasslands at higher altitudes of the sanctuary. A. pindrow (pindrow fir) is the dominant conifer species, in association with Pinuswallichiana A.B. Jacks (Pinaceae) and Picea smithiana
-dominated forest between 1,800 to 3,000 masl with Pinuswallichiana , Quercus spp. and Rhododendron spp. Most of the lower slopes in the north and east of the valley, between 2,000 and 2,900 masl, are covered by thick cool moist broadleaf forest consisting of mixed deciduous and evergreen species, such as
s ey, 1 9 7 1 a B. minutus India ( Himachal Pradesh) Pinuswallichiana
A B J a c k s o n (Pinales: P inaceae)* Walia et al. , 2003 *Dead wood B. mucronatus
Japan Monochamus alternatus H o p e (Coleoptera: Cerambycidae) Pinus densiflora Sieb.
& Zucc., P. thunbergii Par l. , P. pentaphylla