Variation in root morphology of epiphytic orchids along small-scale and large-scale moisture gradients

Abstract

Root morphology is expected to respond to environmental conditions. Two earlier studies reported predictable changes in the structure of the velamen radicum (common in monocotyledons) along rainfall gradients, which was expected from its assumed role in plant-water-relations. The present study expanded on this idea by analysing nine root traits that can be linked to root function, including velamen structure, along two moisture gradients of different spatial scales: 1) along the vertical gradient of a lowland forest in central Panama and 2) along a strong regional rainfall gradient in western Panama. All studied traits (e.g. velamen width, number of xylem poles, lignification of the exodermis) of the 45 orchid species showed substantial intraspecific and interspecific variation, but none of this (within forest) or very little of this (regional gradient) was related to the gradients. Only the community weighted means of velamen width, stele width and xylem pole number varied significantly with rainfall, with substantial effect sizes only found in the latter two traits. Our results clearly disagree with those of earlier publications, which did not include species abundance and/or rigorous statistics in their analyses. This discrepancy highlights that our understanding of the link between velamen form and function is still rudimentary.

SỬ DỤNG ĐẶC ĐIỂM HÌNH THÁI VÀ GEN CHỈ THỊ trnH-psbA ĐỂ NHẬN DẠNG LAN HÀI ĐUÔI CÔNG (Paphiopedilum gratrixianum)

“…Khi phân tích mối liên quan giữa hình thái lan hài với đặc điểm sinh trưởng của chúng, Gruss và cộng sự (2018) nhận thấy, các loài hài có lá đồng màu thường sinh trưởng thích nghi với vùng khí hậu lạnh, còn những loài trên lá có vân thường chịu nóng tốt hơn và thích nghi với biên độ nhiệt độ rộng hơn. Đặc biệt, hình thái, cấu tạo rễ có liên quan chặt chẽ với điều kiện môi trường sống [15].…”

Adaptive Morphophysiological Features of Neottia ovata (Orchidaceae) Contributing to Its Natural Colonization on Fly Ash Deposits

“…It includes species with complex adaptations to pollination by specific insect species and very different life strategies: from epiphytic to terrestrial, from evergreen to completely chlorophyll-free [3,4]. Studies have been conducted on orchids' taxonomy, morphology, ecology, breeding [5][6][7], pollination [8][9][10], genetics [11,12], mycorrhizal association [13][14][15], etc. At the same time, the physiological parameters of Orchidaceae species are still less studied and need much more attention [16].…”

Go with the flow: The extent of drag reduction as epiphytic bromeliads reorient in wind

“…Epiphytes are closer to the interface of vegetation and atmosphere than understorey herbaceous plants, potentially making them more susceptible to changes in atmospheric conditions [e.g., [11][12][13]. Despite the extensive research on the general functional ecology and biology [14][15][16][17][18][19] of vascular epiphytes, the physical disturbance caused by wind on epiphytic growth has received very little scientific attention. There are two ways in which wind acts as a mechanical disturbance to epiphytes-either by directly dislodging individuals from their substrate or by breaking the substrate itself.…”