Circum-Antarctic continental distribution patterns in pteridophyte species

Four major austral continental distribution patterns are evident in pteridophytes. Twenty-two species are completely circum-Antarctic. Another 39 species are partially circum-Antarctic, occurring in Australasia (Australia and New Zealand) and Africa (including Madagascar) but not South America, while 29 are in Africa and South America but not Australasia, and 13 are in South America and Australasia but not Africa. Two hypotheses are considered as explanations for the patterns: continental drift following the breakup of Gondwana and long-distance dispersal. Fossil evidence indicates that the majority of pteridophyte families involved appeared after the southern continents had drifted apart, so long-distance dispersal is likely to explain the distribution of species in these families on now widely separated continents. For those families extant before the break-up, there is no indication in the fossil record that the species involved were present in Gondwana. Aspects of the ecology of the species that are partly or completely circum-Antarctic indicate that long-distance dispersal, rather than continental drift, is a likely explanation for the patterns.     

宜溧山区药用蕨类资源调查

据调查统计,宜溧山区现有蕨类植物26科、44属、82种,其中40种左右有药用价值.对这些药用蕨类的生境、药用功效、利用现状等作了简要阐述,并就其开发和利用提出了相关的建议.     

河南小秦岭自然保护区蕨类植物区系研究

小秦岭自然保护区共计有蕨类植物23科46属107种.其区系基本特征是:地理成分多样,区系联系广泛并具有一定的古老性;以温带性质为主,但有较明显的热带残遗性和亲缘性;特有现象明显,是东亚成分分布中心的一部分;隶属于华北区系,兼有强烈的西北和西南区系特色.     

Fern endemism and its correlates: contribution from an elevational transect in Costa Rica

We studied the distribution patterns of endemic ferns along an elevational gradient of 3400 m in Costa Rica, Central America. We related the endemism patterns of the whole species set and separated for life forms and microhabitats according to topography and environmental factors. Fern species were surveyed in 156 plots each with an area of 400 m², with up to five plots at every elevational step of 100 m. Global range size for every species was compiled from literature data, and species restricted to the mountain range from Costa Rica and adjacent western Panama were defined as endemic (24.5% of all species recorded). We found patterns of endemism rates mostly peaking at mid-elevation, but when separated for different life forms and microhabitats, some deviations from the overall pattern emerged. High constant humidity and reduced surface area were closely related to high levels of endemism. High humidity is discussed as a general predictor for high endemism rates in concert with highest overall richness. Restricted area of elevational belts, indicating a fragmented habitat, leads to a higher degree of population isolation and thus species differentiation. However, both interpretations were not fully supported by our data. Most importantly, endemism rates were fairly low on mountain tops that have the smallest available area in a topographically highly fragmented setting. In contrast, endemic species were more common than widespread species at the highest elevations. History and climatic shifts are assumed to play a role in this respect.     

Palynological assessment of Holocene mangrove vegetation at the American Memorial Park,Saipan, Northern Mariana Islands

Pollen and spores recovered from three cores of Holocene to recent deposits from the island of Saipan indicate the presence of mangrove vegetation, including Bruguiera and Acrostichum, on the island previous to World War II. The occurrence of Casuarina equisetifolia Linneaus 1759, from cores elsewhere on the island of Saipan, at depths predating the arrival of humans to the island, suggest that this tree species is endemic to Saipan rather than a recent invasive species. These findings will assist in replanting native vegetation once destroyed through wartime activities on the island.     

A critical conspectus of Italian Lycopodiaceae

As a result of our work on the Lycopodiaceae account for the Critical Flora of Italy, a new, synonymic inventory of Italian taxa is presented, based on herbarium studies and critical re-examination of extant literature. Three genera with eight species are accepted: Huperzia (1 species), Lycopodiella (1), and Lycopodium (6). An additional, ninth species (Lycopodiella cernua) is listed as a casual alien. The genus Diphasiastrum, accepted in several recent works, is treated at sectional level within Lycopodium (three species and their three hybrids). Lycopodium lagopus ( = L. clavatum subsp. monostachyon) is a recent addition to the Italian flora. Images of five types and Internet URI of other six types are supplied. Dot distribution maps and a dichotomous key to Italian species are provided. It is shown that the family name Urostachyaceae (a family here not separated from Lycopodiaceae) was validly published and has priority over Huperziaceae, for which the oldest name, however, would be Phylloglossaceae.     

Conspectus of Italian Selaginella (Selaginellaceae), with some typifications

An annotated synonymic inventory of Italian Selaginella taxa, a practical key for their identification and their dot distribution maps are presented, as a result of our work on the Selaginellaceae account for the Flora Critica d'Italia. The names Lycopodium helveticum L. and Selaginella denticulata var. platystachya Hieron. are typified.     

Litter‐trapping plants: filter‐feeders of the plant kingdom

Litter‐trapping plants have specialized growth habits and morphologies that enable them to capture falling leaf litter and other debris, which the plants use for nutrition after the litter has decayed. Litter is trapped via rosettes of leaves, specially modified leaves and/or upward‐growing roots (so‐called ‘root baskets’). Litter‐trappers, both epiphytic and terrestrial, are found throughout the tropics, with only a few extra‐tropical species, and they have evolved in many plant families. The trapped litter mass is a source of nutrients for litter‐trapping plants, as well as food and housing for commensal organisms. Despite their unique mode of life, litter‐trapping plants are not well documented, and many questions remain about their distribution, physiology and evolution.–© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 554–586.     

Diffusional limitations explain the lower photosynthetic capacity of ferns as compared with angiosperms in a common garden study

Ferns are thought to have lower photosynthetic rates than angiosperms and they lack fine stomatal regulation. However, no study has directly compared photosynthesis in plants of both groups grown under optimal conditions in a common environment. We present a common garden comparison of seven angiosperms and seven ferns paired by habitat preference, with the aims of (1) confirming that ferns do have lower photosynthesis capacity than angiosperms and quantifying these differences; (2) determining the importance of diffusional versus biochemical limitations; and (3) analysing the potential implication of leaf anatomical traits in setting the photosynthesis capacity in both groups. On average, the photosynthetic rate of ferns was about half that of angiosperms, and they exhibited lower stomatal and mesophyll conductance to CO₂ (g_m), maximum velocity of carboxylation and electron transport rate. A quantitative limitation analysis revealed that stomatal and mesophyll conductances were co‐responsible for the lower photosynthesis of ferns as compared with angiosperms. However, g_m alone was the most constraining factor for photosynthesis in ferns. Consistently, leaf anatomy showed important differences between angiosperms and ferns, especially in cell wall thickness and the surface of chloroplasts exposed to intercellular air spaces.