摘要:

Quantitative and qualitative data on wood and bark are offered for 11 species of lianoid Indomalesian and Asiatic species ofGnetumsectionCylindrostachys.Material of roots was studied for two species, material of an underground stem for one species, and stem material was studied for all species; wood from inside and outside of a large stem ofG. montanumwas analysed (quantitative data do not change with age in this species). Roots have shorter, narrower vessel elements, more numerous per mm2, compared with those of stems; these trends run counter to those in dicotyledons. Roots and underground stems have more abundant parenchyma and less abundant sclerenchyma than do stems. Parenchyma of both roots and stems is rich in starch. All of the species studied here have both fibre‐tracheids and tracheids, but tracheids are not distributed vasicentrically as they are in dicotyledons. Tori are reported for tracheary elements of three species studied here. Vasicentric axial parenchyma (which usually is thick‐walled) is present in all species; thick or thin‐walled diffuse or diffuse‐in‐aggregates apotracheal parenchyma is present in almost all of the species studied. Rays are mostly dimorphic in size, but show various conditions with respect to wall thickness, sclerenchyma presence, and crystal presence. As in other lianoid species ofGnetum, the species of the present study show origin of lateral meristem activity in parenchyma of the innermost cortex. Cortex and bark of the species studied here are relatively uniform in distribution of gelatinous fibres, nests of sclereids, the cylinder of brachysclereids that extends around the stem, and sclerenchymatous phelloderm. Laticifers were observed in bark of only two species studied. Although a few species characters are evident, the species that comprise Sectioncylindrostachysdiffer from each other mostly in degree rather than in presence or absence character state distributions. Secretory cavities are newly reported for

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Leaf morphology has been the subject of several studies inNoNothofagurespecially in the context of the taxonomy and evolutionary relationships of taxa within the genus, which are still controversial. The leaf architecture of 8dombgi, N.betuloidesandN. nitida, dominant trees of temperate forest in southern South America, is compared using venation patterns, landmarks, and entire outlines. In terms of venation patterns N.dombgiand N.betuloideswere more similar to each other than to N.nitida.Similar results were found when differences in shape were analysed by discriminant analyses of shape coordinates (landmarks) and Fourier coefficients (outlines). For both analyses, the fwst discriminant function separatedN. nitidafrom the other two species; these were also distinguished but showed greater overlap with each other. This study, in concert with information from allozyme data confirms the hypothesis of a more ancestral position for N.nitidawithN. dombgiandN. betuloidesbeing more recently derived. In addition to differences in shape, the size component of leaf morphology indicated that whereasN. betuloideshad the smallest leaves,N. dombgispanned the greatest range and has the biggest leaves. Given that the data shown here were obtained from seedlings grown under common‐garden conditions, differences in both shape and size, seem to be important components of leaf morphology that may warrant consideration in characterizing these and other species ofNothofagu

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00743.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Variation in foliar trichomes inCroton(Euphorbiaceae) is reviewed, and the terminology clarified by redefinitions and illustrations of terms. Evolution of trichome types appears to proceed from branched (stellate or fasciculate) hairs to simple and dendritic ones. A systematic enumeration characterizes the trichome morphology in 36 of the 40 sections, with citation of the 120 species examined.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00744.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Paphiopedilum uillosumwas studied in hill evergreen forests (at up to 35 m above ground level) in North Thailand between 1990 and 1994. Flowering lasted 4.5 months: flower longevity 2–3 months. During 224 hours of flower‐watching, less than 100 specimens of Syrphidae (Diptera) were seen in the vicinity of the flowers; 15 cases of pollen acquisition were mainly by femaleEplsyrphus alternans, Syrphus fulvifacies, Betasyrphus serariusamong 6 spp. of pollinators. Populations peaked during the main flower opening period, one month before the maximum number of open flowers was reached in early February. The flowers are ‘kettle‐traps’ without known reward, luring mainly by food deception. Long distance attraction is probably by a urine‐like odour (attraction to mammalian excretions had hitherto been little reported) and colour contrast. Close range lure is by the glittering staminode (probably mimicking droplets of honeydew/moisture) centred by a slippery wart (faking a perch) at which pollinators fly, immediately losing their grip and tumbling into the pouch, preventing wing action and falling being disrupted by a trough‐shaped frame. Escape is up the tunnel, past the stigma, to the exit where, pressed by several mechanisms against the anther, the hoverfly scoops off very sticky pollen which has a viability of at least 8 weeks. Capsule formatio

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00745.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00742a.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY