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summary Young spruce (Pirea abies [L.] Karst; 2-yr) and beech trees (Fagus sylvatica L.; current-year and 1-yr-old seedlings) were grown under field conditions at a rural site near the city of Base] (Schonenbuch; 400 m above sea level) and 2-yr-old spruce trees at an elevated montainous site (Wengernalp; 1890 m above sea level). The plants were exposed in open-top-chambers (OTC) either to charcoal-filtered air or ambient air with ozone being the predominant air pollutant at both sites. The exposures lasted up to 1 yr. At the end of the growth period the plants were harvested and the pool sizes of the major non-structural carbohydrates were determined. Exposure to ambient air compared with filtered air controls caused an increase of glucose, fructose, pinitol, starch and, in some cases, sucrose in needles whereas carbohydrate contents in roots and twigs of spruce were reduced, in particular at Wengernalp. In beech saplings at Schonenbuch, a significant rise of sucrose and, in some cases, of raffinose, together with a significant reduction of glucose and fructose was observed in buds, leaves, twigs, and roots in ambient air compared with filtered air. In phloem exudates of current year beech seedlings, a 54–160 higher content of carhohydrates was found in ambient air than in filtered air. In roots of the beech saplings, the amount of soluble carbohydrates increased and starch contents mostly decreased. In general, starch storage in roots and stems was more abundant in beech trees. Spruce, especially at the mountainous site, accumulated high amounts of soluble carbohydrates in needles, in particular glucose.

Recent collections and new morphological information justify the transfer of Pireella cavifolia to Porotrichum and its treatment within Neckeraceae in the Moss Flora of Mexico. New morphological evidence and a review of recent collections of Pireella cavifolia (Card. & Herz.) Card. have led to the following reevaluation of its relationships. Pireella cavifolia is a small, dendroid moss known from the West Indies and Mexico south through Guatemala (San Marcos, Croat 40961A, MO) to Panama (Darien, Allen 8917C, MO) and Colombia (Risaralda, Wolf 1435, MO). The species has undifferentiated alar cells and clearly differs from other members of Pireella in having obovate leaves that are broader above and lack a distinct flattened apical portion. The sporophyte of P. cavifolia is unknown. Allen (1987), in a broad survey of pseudoparaphyllia in the Pterobryaceae, found that the family is characterized by the presence of filamentous pseudoparaphyllia. In his survey, the only two species that lacked such structures were considered misplaced in the Pterobryaceae. Pireella cavifolia does not have filamentous pseudoparaphyllia; instead, it appears to have either folious pseudoparaphyllia or rudimentary branch leaves around its branch primordia. The absence of sporophytic evidence for P. cavifolia makes its placement problematical, but on the basis of its lack of filamentous pseudoparaphyllia we exclude the species from the Pterobryaceae. The presence in this species of folious structures around the branch primordia, a dendroid habit, undifferentiated alar cells, and especially the occasional production of flagelliform gemmiferous branches all indicate the Neckeraceae as a likely placement for it. Within the Neckeraceae, Porotrichum could accommodate it. This transfer is therefore made so that the species can be treated within the Neckeraceae for the Moss Flora of Mexico. Porotrichum cavifolium (Card. & Herz.) Magill & Allen, comb. nov. Basionym: Pirea cavifolia Card. & Herz. in Card., Rev. Bryol. 38: 39. 1911. Pireella cavifolia (Card. & Herz.) Card., Rev. Bryol. 40: 17. 1913. TYPE: Mexico. Hidalgo: Honey-station, Pringle 15668 pro parte (holotype, PC). Illustrations: Theriot (1940, pl. 54, 5a-5f as Jaegerinopsis ramosa); Arzeni (1954, pls. 22-23). Acknowledgment. We thank the anonymous reviewer of the manuscript for useful comments.