Synopsis of Grimmia Hedw. in New Zealand,including Grimmia wilsonii sp. nov.

Abstract

The New Zealand Grimmia Hedw. specimens from AK, AKU, BM, CHR, OTA and WELT have been revised and a bryological field trip to the New Zealand Southern Alps was made to study specimens in their natural habitats. As a result of the revision and the field trip, G. anodon, G. austrofunalis, G. orbicularis and G. tortuosa were added to the moss flora. A key is presented, the species are briefly discussed and Grimmia wilsonii H.C. Greven sp. nov. is described and illustrated.     

Ein neuer Standort vonBryum Venturii De Not

Ohne Zusammenfassung     

Grimmia homodictyon Dixon

Abstract

We examined photosynthetic responses of two dominant pleurocarpous mosses, Actinothuidium hookeri (Mitt.) Broth. and Hylocomium splendens (Hedw.) Schimp. to low-level nitrogen (N) addition. The study was conducted in an old-growth fir forest on the eastern Tibetan Plateau. The added N, 1 g N/m², was mainly absorbed by the new-growth. The concentrations of chlorophyll a and b both increased 8 days after N addition. The quantum yield of Photosystem II (Φ_PSII) also increased. However, no significant changes were found in terms of gas exchange parameters. The mass-based CO₂ assimilation rate, chlorophyll a content, and chlorophyll a/b ratio (which is related to antenna size of the photosystem), of H. splendens were all higher than those of A. hookeri. Shoot mass per area (SMA) of H. splendens was lower than that of A. hookeri. We conclude that the photosynthetic rate was less sensitive to low-level N addition than chlorophyll contents and chlorophyll fluorescence parameters, suggesting other limiting factors in the photosynthetic process. Additionally, the faster growing H. splendens has a higher photosynthetic capacity than A. hookeri, allocating fewer resources to structural tissue.     

Spore wall morphology and dehiscence pattern in the liverwort Fossombronia caespitiformis De Not.

Abstract

The spore wall morphology and first germination stages of Fossombronia caespitiformis are described. The spores are markedly heteropolar and catalept. The boundary line, which separates the proximal and distal faces, is shifted toward the proximal pole. The spore coat breaks along this boundary line allowing the protonemal tube to protrude. The dehiscence pattern can be considered tangential.     

The Localization of Lead in the Lichen Ramalina duriaei (De Not.) Bagl.

In an attempt to ascertain whether the lichen Ramalina duriaei could be employed to biomonitor atmospheric lead pollution, specimens of this lichen were exposed to Pb (NO₃)₂ solutions and a buffered solution (tartaric acid/sodium bitartrate, pH 2.8) of sodium rhodizonate (C₆O₆Na₂) was used to locate lead in their thalli. The procedure entailed exposure of the lichen to 0, 5, 50 and 100 ppm Pb for 5 min and 1 h and the subsequent determination of the lead contents from photographs of the thalli. Distribution of lead in different parts of the thallus was assessed after exposure of the lichens to 2 ppm Pb (9 h or three d), 50 ppm (45 min) or 200 ppm (4d). Cross sections of vegetative parts of the thallus and of the apothecia revealed that lead penetrated into the cortical cells of the thallus but not into the algal cells of the phycobiont nor the ascospores or medullary cells. The observed massive penetration of lead into cortical cells supports the notion that Ramalina duriaei is sensitive to atmospheric lead pollution.     

A new Middle Eastern Grimmia

Abstract

Photosynthesis, respiration, net assimilation, chlorophyll b concentration, and levels of potassium, calcium, magnesium and iron were measured in 2 cm shoot segments of Pleurozium schreberi in order to examine patterns of physiological decline with ageing in a continuously growing species. Photosynthesis and chlorophyll b levels declined rapidly after the apical shoot segment and were undetectable after a distance of 8 cm from the shoot apex. Respiration rate also fell rapidly at first but then declined more gradually and some respiration was detected in all shoot segment samples. Potassium and magnesium levels declined approximately linearly in relation to segment number. Calcium levels, expressed on a concentration per unit weight basis, became progressively higher in older segments but the calcium content per segment may actually decline with age. The disparity may be due to a decline in the proportion of cytoplasm compared with cell wall material in older segments.

No clear division could be made between living and dead shoot segments. Different physiological processes decline at different rates as ageing occurs and the importance of the age structure of shoot samples is discussed in relation to design of physiological experiments.     

Grimmia agassizii (Sull. & Lesq.) Jaeg. in Britain

Abstract

The marked differences between Plagiochila spinulosa (Dicks.) Dum. and P. killarniensis Pears. pointed out by Paton (1977) are confirmed and added to by further ones. As a result the two species are placed in different sections Spinulosae and Zonatae, respectively. For each of the two species the full synonymy including new synonyms and new lectotypifications and a comprehensive list of studied specimens and a distribution map are presented. In appendix, P. porelloides (Torrey ex Nees) Lindenb. is recorded from Madeira, a species new to Macaronesia.     

Microsporogenesis in Brachiaria dictyoneura (Fig. & De Not.) Stapf (Poaceae: Paniceae)

Microsporogenesis was analyzed in five accessions of Brachiaria dictyoneura presenting x = 6 as the basic chromosome number. All accessions were tetraploid (2n = 4x = 24) with chromosome pairing in bi-, tri-, and quadrivalents. The recorded meiotic abnormalities were those typical of polyploids, including precocious chromosome migration to the poles, laggard chromosomes, and micronucleus formation. The frequency of these abnormalities, however, was lower than those reported for other polyploid accessions previously analyzed for other Brachiaria species. Cell fusion and absence of cytokinesis were also recorded in some accessions, leading to restitutional nucleus formation in some cells. Genetically unbalanced microspores, binucleate, and 2n microspores were found among normal meiotic products as results from these abnormalities. The limitation in using these accessions as pollen donor in interspecific crosses with sexual species with x = 7 or x = 9 in breeding programs is discussed.