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Variation in the wood structure of Alnus nepalensis D. Don (Betulaceae) in relation to tree size and habitat altitude was studied in four areas of Nepal: Tamur, Rolwaling, Budi Gandaki, and Bajhang-Khaptad. Alnus nepalensis is a pioneer tree distributed in the Himalayas from northern India to southwestern China and grows throughout Nepal in a wide altitudinal range from 200 m in the tropical zone to 3030 m at the upper limit of the temperate zone. Ecological trends in the wood structure of Alnus nepalensis varied between the studied areas, distinct in the Tamur area, but indistinct in other areas, and tended to be detected in areas with specimens from altitudinal ranges of 2000 m. When all the specimens were separated at 1800 m in elevation and analyzed as two altitudinal groups, features of vessel size and distribution and the ratio of solitary vessels had a significant correlation with tree height in both groups, and tall trees tended to have larger, more solitary vessels. Vessel element and fiber lengths did not have any significant trends in the lower group but had a negative correlation with altitude in the upper group along with the reduction of tree height. Thus, vessel size seems to facilitate the height growth of this pioneer tree, and shorter tracheary elements and more vessel multiples seem to be related to the adaptation of smaller trees at higher elevations. [ABSTRACT FROM AUTHOR]

Erioscirpus (Cyperaceae) is distributed mainly in the Himalayas, comprising two species: E. comosus and E. microstachyus. Recent authors have not recognized Erioscirpus as a distinct genus, but included it either in Eriophorum or Trichophorum, and always placed in tribe Scirpeae. However, as past authors have previously noted, Erioscirpus is quite different from Eriophorum and Trichophorum in some morphological features and in ecological preferences. In this study, we aimed to clarify the phylogenetic position of Erioscirpus using plastid and nuclear DNA sequence data for E. comosus from Nepal and Myanmar and E. microstachyus from India. We found that Erioscirpus was nested in tribe Cypereae, among the Ficinia clade with Dracoscirpoides, Ficinia, Hellmuthia, Isolepis and Scirpoides, which are predominantly distributed in the Mediterranean zones of the Southern Hemisphere. In contrast, Eriophorum and Trichophorum formed a clade with members of the tribes Cariceae, Dulichieae or Scirpeae, which are mainly distributed in the Holarctic zones of the Northern Hemisphere. It is thought that the common character, cotton-like long perianth bristles, shared by Erioscirpus, Eriophorum and Trichophorum, has evolved independently several times as a mechanism promoting wind dispersal. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170, 1-11. [ABSTRACT FROM AUTHOR]