A systematic histological study of palm fruits. VI. Subtribe Linospadicinae (Arecaceae)

The pericarp structure of representative species of the four genera of the subtribe Linospadicinae is described and compared. Tissues found in the pericarp of this group are similar to those found in other subtribes of the Areceae, with no characters unique to the subtribe and nothing to suggest its closest affinities. The four genera, as well as each species examined, do show distinctive pericarp features, however.Laccospadix andLinospadix are similar, both with a single series of fibrous, bundles and an outer series of prominent raphide-bearing cells dominating the pericarp. In bothHowea andCalyptrocalyx, a complex exocarp forms from a series of fibrous bundles and brachysclereids, but each genus has other distinctive characters.Howea has vascular bundles in the exocarp zone, an outer series of raphide-bearing cells, and a conspicuously thickened locular epidermis. Based on a limited sample of four species, raphide-bearing cells appear to be always interior to the exocarp inCalyptrocalyx, and the locular epidermis is thin.     

Biomechanics and development of rattans: what is special about Plectocomia himalayana Griff. (Calamoideae,Plectocomiinae)?

Mechanical and morphological studies of Plectocomia himalayana (subtribe Plectocomiinae) revealed characteristics that differ strongly from species of subtribe Calaminae ( Calamus and Daemonorops ). In species of Calaminae tested previously, the contribution of the leaf sheath drastically increases stiffness in juvenile axes and towards the apex of older plants. In P. himalayana the relative contribution of the leaf sheath to axis stiffness is less and leaf sheath senescence does not strongly reduce axial stiffness as observed in Calamus and Daemonorops . Natural aerial branching, only described in Korthalsia and Laccosperma among rattans, is common in P. himalayana . Aerial branching and adventitious roots occur frequently along old stems allowing autonomy of stems, following mechanical injury and promoting vegetative propagation. The climbing habit is known to have evolved at least twice within the Calamoideae. The results observed here suggest that climbing habits may differ in detail and that different 'climbing strategies' may have evolved within the subfamily Calamoideae resulting from: (1) variable stem flexibility, (2) the variable mechanical role of the leaf sheath ( Calamus–Daemonorops ) and (3) production of branches and aerial roots conferring a higher degree of architectural plasticity ( Plectocomia ).  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 83–91.     

上海地区红棕象甲的耐寒性研究

红棕象甲Rhynchophorus ferrugineus (Olivier)是我国危害棕榈科植物的重要入侵害虫, 为探明其越冬抗寒性, 利用过冷却点测定仪测定了红棕象甲上海种群不同虫态的过冷却点, 在低温箱内测定了该虫不同虫态的耐寒性, 然后结合田间越冬模拟试验、气象资料和寄主分布情况, 初步确定了红棕象甲在我国的越冬北界。结果表明： 红棕象甲过冷却点随虫态的发育程度的升高而下降, 卵、1龄幼虫、5龄幼虫、9龄幼虫和成虫的平均过冷却点分别为-5.92, -6.42, -7.19, -7.43和-11.84℃, 过冷却点由高到低的顺序依次为: 卵>幼虫>成虫。在6, 24, 48和72 h 4个时间处理下, 各虫态在低温与存活率之间呈显著或极显著的logistic回归, 半致死温度（Ltemp₅₀）均随处理时间的延长而上升, 不同虫态在处理72 h 后, 卵、1龄幼虫、5龄幼虫、9龄幼虫和成虫之间的Ltemp₅₀分别为1.61, -1.67, -2.39, -2.40和-0.40℃, 各虫态耐寒性由弱到强的顺序依次为: 卵<成虫<幼虫。红棕象甲不同发育阶段的过冷却点与其耐寒性并不完全相关, 幼虫和成虫均可能是该虫的越冬虫态。连续两年的田间模拟越冬试验表明, 在上海地区, 红棕象甲的幼虫和成虫的越冬存活率均在60％以上, 说明红棕象甲在上海地区是可以越冬的。根据这些结果, 结合寄主分布情况, 初步将红棕象甲在我国的越冬北界定于北纬35°附近, 即1月份0℃等温线左右。     

Molecular genetic analysis of two native desert palm genera,Washingtonia and Brahea,from the Baja California Peninsula and Guadalupe Island

The complex geological and ecological processes that have generated high levels of biodiversity and endemism in the Baja California Peninsula have been the subject of intensive study. However, relatively little is known about phylogeography of the iconic endemic palm species of this region. We therefore analyzed a total of 2,294 bp of chloroplast and 738 bp of nuclear sequence data in 169 samples of five native palm species from Baja California, Sonora and Guadalupe Island. We found that Washingtonia and Brahea palms had low levels of genetic diversity and were highly structured, with the majority of species and major geographic regions being characterized by distinct haplotypes. We also found strong support for currently recognized species in Washingtonia, but our results were less clear cut for Brahea due to haplotype sharing. Furthermore, patterns of population structure were broadly consistent with historical vicariant events such as the inundation of the Isthmus of La Paz, the formation of the Sea of Cortez, and the more recent colonization and isolation of Guadalupe Island's palms. Our findings contribute toward a growing appreciation of the complexity of plant responses to past geological changes and also provide valuable baseline genetic data on relict American palm species.     

铜壁关自然保护区藤本植物多样性研究

为了解铜壁关自然保护区藤本植物现状,经实地考察对其组成和多样性进行了研究。结果表明:本区有藤本植物676种,隶属于65科209属,双子叶藤本植物具有明显优势,计56科192属597种。生活型组成以高位芽藤本种类为主,占藤本植物种数的81.51%。攀援方式中缠绕藤本具有明显优势,占藤本植物种数的53.99%,并提出了斜倚类藤本植物的概念。极高的降雨量、悬殊的海拔、多样的生境类型、广泛发育的各类原始阔叶林,是本区藤本植物极为丰富的根本原因。     

Productivity and management of Phytelephas aequatorialis (Arecaceae) in Ecuador

Phytelephas aequatorialis is endemic to western Ecuador. Vegetable ivory (tagua, the hard endosperm) and leaves for thatch (cade) are harvested from the palm and commercialised. Export of vegetable ivory from Ecuador reached a value of 14 million US$ in 2011, making it the second most important product from native palms in the country. Vegetable ivory and leaves are harvested mainly from the wild, although the palm is occasionally cultivated. Most seeds harvested for vegetable ivory are collected from the ground. In times of high demand, however, some harvesters collect immature infructescences; these young seeds are of inferior quality and unsuitable for the fabrication of tagua discs for export. Premature harvest reduces the amount of fully mature, high‐quality seed leading to resource limitation for the processing industry that already is unable to satisfy international demand. Fruit production in lowland agroforestry systems strongly correlates to the level of exposure to light. The development of infructescences takes 3 years in the lowlands (≤93 m a.s.l.) and over 4 years on the Andean slopes at around 1400 m a.s.l. Data from 365 tagged individuals show that male palms produce significantly more leaves than female palms and palms growing in the shade produce fewer, but longer and higher quality leaves for thatch. Leaf harvest has little impact on leaf production, but substantially reduces fruit production. Natural regeneration of Phytelephas populations in pastures is negatively affected, rendering the survival of these populations problematic. Sustainable use and commercialization of the two partially exclusive and locally competing products tagua (vegetable ivory) and cade (leaves for thatch) must be carefully designed. Application of unsustainable practices in the harvest of seeds and leaves, population decline in pastures, and resource limitation in the processing industry represent the main challenges in the sustainable use of this valuable palm species in the future.     

Impact assessment of intense sport climbing on limestone cliffs: Response of rock-dwelling land snails

Exposed limestone cliffs in the Swiss Jura Mountains harbour a diverse gastropod community with some rare species. Sport climbing has recently increased in popularity on these cliffs. We examined the effects of sport climbing and microtopographical features of rock faces on terrestrial gastropods by assessing species diversity and abundance on climbing routes and in unclimbed areas of seven isolated cliffs in the Northern Swiss Jura Mountains. We considered exclusively living individuals resting attached to rock faces. In total, 19 gastropod species were recorded. Six of them were specialized rock-dwelling species, whose individuals spend their entire life on rock faces, feeding on algae and lichens. Plots along climbing routes harboured fewer species of rock-dwelling snails as well as other gastropod species (usually living in the leaf litter layer at the cliffs’ base) than plots in unclimbed control areas. Similarly, both the density of individuals and frequency of occurrence in plots were reduced in both groups of snails on climbing routes. The complexity of the rock surface had little influence on the species richness and abundance of gastropods. Pyramidula pusilla, the species with the smallest shell and a preference to rest underneath overhangs, was less affected by sport climbing than snail species with larger shells and a preference to rest on exposed smooth rock surface. Our findings indicate land snail diversity and abundance are suitable indicators for impact assessment in rocky habitats. Future management plans and actions should therefore not only rely on plants; they ought to consider also gastropods and other invertebrates. Any management plan should include a comprehensive information campaign to show the potential impact of intensive sport climbing on the specialized flora and fauna with the aim of educating the climbers and increasing their compliance with such measures.     

A systematic histological study of palm fruits. IV. Subtribe Oncospermatinae (Arecaceae)

Pericarp histology in the Oncospermatinae reveals distinctive characters at the generic level but no unique characters at the subtribal level. Pericarp structure is diverse but parallels the diversity found in other subtribes of the Areceae. The subtribe appears to be divisible into two distinct groups: one in which sclereids alone provide the primary protective barrier in the outer fruit and one in which fibrous bundles, some-times in combination with brachysclereids, form the outer barrier. This division of the subtribe supports similar conclusions derived from morphological data.     

Release of Endogenous and Accumulated Exogenous Amino Acids from Slices of Normal and Climbing Fibre-Deprived Rat Cerebellar Slices

Efflux of various amino acids from slices of rat cerebellar hemispheres was determined under resting or depolarizing conditions. It was increased under high K+(50 mM) as compared to low K+ (5 mM) conditions by 1258 pmol/mg protein for aspartate, 478 for gamma-aminobutyric acid (GABA), 44,693 for glutamate, and 615 for glycine. These were significantly higher than the corresponding values obtained under low-Ca2+ (0.1 mM), high-Mg2+ (12 mM) conditions, whereas for 11 other amino acids the K+-induced efflux was similar under normal and low-Ca2+ concentrations. The K+-induced efflux of exogenously accumulated L-[3H]aspartate, D-[3H]aspartate, and L-[3H]glutamate was higher by factors of 2, 5.8, and 6.3, respectively, under normal Ca2+ conditions, as compared with low-Ca2+, high-Mg2+ conditions. After climbing fibre degeneration induced by destruction of the inferior olive with 3-acetylpyridine, release of endogenous aspartate and exogenous L-[3H]glutamate and D-[3H]aspartate was significantly reduced, by 26%, 38%, and 27%, respectively. These results support the hypothesis that climbing fibres may use aspartate or a related compound as a neurotransmitter. In rat cerebellar tissue, L-[3H]glutamate and L-[3H]aspartate differ in several aspects: (1) L-[3H]glutamate uptake was 4 times higher than that of L-[3H]aspartate; (2) fractional rate constant of K+- evoked release of L-[3H]aspartate was 7% X 2.5 min-1, and of L-[3H]glutamate 36% X 2.5 min-1; and (3) specific activity of L-[3H]glutamate in the eluate collected during K+ stimulation was 3.5 times the value in the tissue, whereas for L-[3H]aspartate, specific activities in the eluate and tissue were similar.