A fossil Vallisneria plant (Hydrocharitaceae) from the Early Miocene freshwater deposits of the Most Basin (North Bohemia)

A new fossil species of Vallisneria (V. janecekii Bogner & Kva?ek, sp. n., Hydrocharitaceae) is reported from Early Miocene freshwater lake deposits of the North Bohemian brown coal basin (Czech Republic). It is based on a single fragmentary sterile plant bearing two clusters of ribbon-shaped widely serrulate leaves on a short rhizome. It is a potential producer of seeds described from equivalent and slightly older deposits in Saxony (Germany) as Vallisneria ovalis Mai.     

Frugivory and Seed Dispersal by Brown Lemurs in a Malagasy Tropical Dry Forest

In the Ankarafantsika tropical dry forest (northwestern Madagascar), the common brown lemur (Eulemur fulvus fulvus) is the largest frugivore and probably the sole disperser of large‐seeded plants (seed diameter > 10 mm). To investigate seed dispersal by this primate, I recorded the feeding activities of a troop; also conducted fecal analyses, germination trials on defecated seeds, and a vegetation survey over 1 yr (beginning Dec 2006). Brown lemurs mostly consumed fruit (68%). The fruit of Vitex beraviensis was the most exploited resource (21% of total feeding time). Among dung samples, 1126 contained intact seeds of 70 plant species, with a median of six seeds and two species per sample. These data indicate that the brown lemur population dispersed approximately 9854 seeds/km²/d. Although the number of annually defecated seeds was overwhelmingly the largest in Grewia triflora, many of the small seeds were often clumped in dung piles. In contrast, large seeds of V. beraviensis occurred in the largest number of dung samples. The rate and time of seed germination in V. beraviensis were improved by passage through brown lemur guts. Therefore, V. beraviensis may readily establish seedlings in sites of brown lemur fecal deposition. Vitex beraviensis and brown lemurs are probably involved in a strong mutualism. Twenty‐three large‐seeded plants were probably dependent on brown lemurs for seed dispersal and some of these species were common trees in the forest. Maintenance of these key plant–animal interactions will probably contribute to the conservation of species diversity and intact regeneration of the Ankarafantsika forest.     

Post-dispersal predation on Pinus sylvestris seeds by Fringilla spp: ground substrate affects selection for seed color

Background matching might lower the risk of seeds being eaten by seed predators that search visually. In aviary experiments, we analyzed the selection of diff erent-colored seeds by ground-feeding finches (Fringillacoelebs and F.montifringilla) against four naturally occurring forest soil substrates. The substrates were fresh burn (black), 6-year-old burn (brown), mineral soil (pale yellow) and Pleuroziumschreberi feather moss (green). We used color-sorted seeds of Pinussylvestris, a species with a large natural variation in seed color, ranging from pale yellow to black. Although seeds were scattered on the substrates at a density of only 91 seeds m⁻², birds removed seeds effectively. Both bird species found more pale than dark seeds on the fresh burn substrate. F. montifringilla also recovered more pale than dark seeds on the old burn, and more dark than pale seeds on mineral soil. In moss, the birds found very few seeds compared to the other substrates, and there was no color discrimination. P.sylvestris is frequently regenerating after fire, suggesting that dark seeds would be favored under selection from visually searching predators. Fire-adapted conifers with serotinous cones, e.g., Pinuscontorta ssp. latifolia, which spread their seeds primarily on freshly burnt surfaces, produce uniformly black or dark brown seeds. However, regeneration of the non-serotinous P.sylvestris is often extended for several years after a fire, during which substrate color and structure change. This may have helped to maintain variation in seed color. When regeneration of a plant species occurs on a substrate of uniform color, we believe that selection by visually searching seed predators will result in the evolution of cryptic seed color. Received: 16 August 1996 / Accepted: 30 November 1996     

Traits of fatty acid accumulation in dimorphic seeds of the euhalophyte Suaeda salsa in saline conditions

The mechanism on of how salinity affects seed fatty acids accumulation remains unclear in halophytes. The present results revealed that the content of total unsaturated fatty acids in black seeds was higher than in brown seeds in the euhalophyte Suaeda salsa under controlled saline conditions. Salinity (200?mM NaCl) significantly increased the total oil content, unsaturated acid/saturated acid ratio, and content of α-linolenic acid (C18:3) (ALA), especially in brown seeds. The most abundant fatty acid in dimorphic seeds is linoleic acid (C18:2) (>70%). It appears that more ALA accumulated in brown seeds compared to black seeds. The enzyme activity of omega-3 fatty acid desaturase (ω-3 FAD) in brown seeds was much higher than that in black seeds, but salinity had no significant effect on the activity of ω-3 FAD in both brown and black seeds. The relative expression of SsFAD7 was increased by salinity, and the value in brown seeds was much higher than that in black seeds. This means salinity can, salinity can improve the quantity of fatty acids in dimorphic seeds of S. salsa, and the enzyme of ω-3 FAD and SsFAD7 may involve in the accumulation of ALA in dimorphic seeds under salinity.     

Effects of salinity and nitrate on production and germination of dimorphic seeds applied both through the mother plant and exogenously during germination in Suaeda salsa

Salinity and nitrogen are two important environmental factors that affect the distribution of halophytes in their natural saline habitats. Seeds of the euhalophyte Suaeda salsa L. were harvested from plants that had been treated with 1 or 500 mm NaCl combined with 0.5 or 5 mm NO₃^?‐N (nitrate) for 115 days in a glasshouse. Germination was evaluated under different concentrations of NaCl and nitrate. Plants exposed to high salinity (500 mm ) and low nitrate (0.5 mm ) tended to produce heavy seeds. Either high salinity (500 mm ) or high nitrate (5 mm ) increased the brown/black seed ratio. The concentrations of Na⁺, K⁺, and Cl^? were higher in brown than in black seeds, and NO₃^? concentrations were higher in black than in brown seeds, regardless of NaCl and nitrate treatments during plant culture. Regardless of NaCl and nitrate concentrations during germination, seeds from plants grown with 0.5 mm nitrate generally germinated more rapidly than seeds from plants grown with 5 mm nitrate, and the difference was greater for black than for brown seeds. Exogenous nitrate during germination enhanced the germination of brown seeds less than that of black seeds. Producing more brown seeds and heavy black or brown seeds appears to be an adaptation of S. suaeda to saline environments. Producing more black seeds, which tend to remain dormant, should reduce competition for nitrogen and appears to be an adaptation to nitrogen‐limited environments. In conclusion, nitrate provided exogenously or by mother plants to black seeds may act as a signal molecule that enhances the germination of black S. suaeda seeds.     

The role of invertebrates in seedling establishment in a heterocarpic plant,Atriplex sagittata

Seed heteromorphism is a marked character of many Chenopodioideae (Amaranthaceae). Seed morphs differ in dormancy, germination and seedling biology, but differences in their predation have not yet been studied. Atriplex sagittata produces small black dormant and large brown non‐dormant seeds. In this study, the timing of seed release and seedling establishment were ascertained, and their consumption by invertebrates (carabids, isopods and slugs) was studied. Seeds dispersed in the autumn passed the winter on the ground surface, protected from invertebrate predation by low temperatures. In the following vegetative season, ungerminated black seeds exposed to predation on ground surface were preferred by a large carabid species, Pseudoophonus rufipes. Some black and all brown seeds escaped predation by germinating in early spring. The seedlings were little endangered by carabids and isopods but were preferred by an invasive slug, Arion vulgaris, the feeding of which can exterminate seedlings at places in which slugs are abundant. Invertebrate predation is important factor of seed and seedling mortality of A. sagittata and seed heteromorphism modifies its intensity and timing.     

Non-native mammals are weak candidates to substitute ecological function of native avian seed dispersers in an island ecosystem

Although prominent examples exist of non-native species causing substantial ecological harm, many have neutral or positive effects, including filling surrogate roles once performed by extinct native organisms. We tested the ecological roles of two non-native mammals as seed dispersers or seed predators in Guåhan, which, due to invasive brown tree snakes (Boiga irregularis), is devoid of native seed dispersers–birds and bats. We conducted feeding trials with captive rats (Rattus spp.), which are present but uncommon due to predation by snakes, and pigs (Sus scrofa), which are abundant. We examined if and how they interacted with common forest fruits. We then compared how any gut-passed or animal-handled seeds germinated compared to seeds left in whole fruit or depulped seeds. Rats and pigs interacted with most of the fruits and seeds (>80%) that they were fed. Of those, most seeds were destroyed—78% for rats and 90% for pigs, across both native and non-native plant species. Compared to seeds germinating within whole fruits, rats improved germination of the seeds that they handled without ingesting, while pigs diminished the germination of seeds that they handled. The small percentage of seeds (approximately 1.5% for rats and 5% for pigs) that survived gut passage germinated in higher proportions than those in whole fruits. Percentages of seed survival to germination are lower than found in similar studies with native avian frugivores. Our results indicate that pigs and rats have mixed effects on seeds, but are not suitable surrogates for native seed dispersers.     

The role of the seed coat in adaptation of dimorphic seeds of the euhalophyte Suaeda salsa to salinity

The role of the seed coat in adaptation of dimorphic seeds of the euhalophyte Suaeda salsa to salinity was investigated during germination and early seedling growth. Black and brown seeds were treated with chloroform for 1 min before the extract was used to analyze waxes and the seeds to investigate the protective role of the seed coat under saline conditions. Waxes in black seed coats were more abundant than those in brown seed coats. Salinity (500 mM NaCl) increased the concentration of Na⁺ and decreased the concentration of K⁺ in both black and brown seeds regardless of chloroform treatment. Chloroform treatment alone (in the absence of NaCl) had no effect on the concentration of Na⁺ or K⁺ in black or brown seeds and in the presence of 500 mM NaCl had no effect on the concentration of Na⁺ or K⁺ in brown seeds. However, chloroform treatment increased Na⁺ and decreased K⁺ in black seeds with 500 mM NaCl. A change of MDA (malondialdehyde) concentration in black and brown seeds treated with or without chloroform was similar to the change of Na⁺ concentration. High salinity (1500 mM NaCl) pretreatment for 40 days had a less adverse effect on germination of black seeds compared with brown seeds after they were transferred to fresh water regardless of chloroform treatment. Similar results were found for seedling emergence. In conclusion, a black seed coat may be more protective than a brown seed coat, probably by shielding the embryo from ion toxicity, because of its higher content of waxes. Thus black seeds can better maintain seed viability than brown seeds for extended periods under hypersaline conditions.     

<Emphasis Type="Italic">Hortaea acidophila</Emphasis>, a new acid-tolerant black yeast from lignite

A hitherto undescribed black yeast was isolated from an extract of brown coal containing humic and fulvic acids at pH 0.6. The fungus showed morphological similarity to some members of the genus Exophiala (Chaetothyriales) and of Hortaea (Dothideales). Based on SSU rDNA sequence similarity to meristematic members of the Dothideales, the new species was accommodated in Hortaea, which presently contains only a single, halophilic species, H. werneckii.     

Germination dimorphism in Suaeda acuminata: A new combination of dormancy types for heteromorphic seeds

Desert annual Suaeda acuminata produces two morphologically distinct types of seeds on the same plant. The main aims of our study were to compare germination characteristics of the dimorphic seeds, ascertain their dormancy types and give the hormonal explanation. The two seed types of S. acuminata absorbed water at different rates with brown seeds imbibing water faster. Germination percentages of brown seeds were significantly higher than those of black seeds in all temperature and light regimes tested. Eight weeks of cold stratification did not break dormancy of black seeds, whereas exogenous GA₃ promoted germination. Excised embryos of untreated black seeds produced normal seedlings. Contents of ZR, GA₃ and ABA of brown seeds were significantly higher than that of black seeds; while contents of IAA of black seeds were significantly higher than that of brown seeds. Brown seeds of S. acuminata are non-dormant, whereas black seeds have intermediate physiological dormancy (PD). Interaction among ZR, ABA and GA₃ may play an important role in dormancy status of both seed types. This is the first report of non-dormancy and intermediate PD in a heteromorphic species.     

Comparison of germination and seed bank dynamics of dimorphic seeds of the cold desert halophyte Suaeda corniculata subsp. mongolica

Background and Aims

Differences in dormancy and germination requirements have been documented in heteromorphic seeds of many species, but it is unknown how this difference contributes to maintenance and regeneration of populations. The primary aim of this study was to compare the seed bank dynamics, including dormancy cycling, of the two seed morphs (black and brown) of the cold desert halophyte Suaeda corniculata and, if differences were found, to determine their influence on regeneration of the species.

Method

Seeds of the two seed morphs were buried, exhumed and tested monthly for 24 months over a range of temperatures and salinities, and germination recovery and viability were determined after exposure to salinity and water stress. Seedling emergence and dynamics of the soil seed bank were also investigated for the two morphs.

Key Results

Black seeds had an annual dormancy/non-dormancy cycle, while brown seeds, which were non-dormant at maturity, remained non-dormant. Black seeds also exhibited an annual cycle in sensitivity of germination to salinity. Seedlings derived from black seeds emerged in July and August and those from brown seeds in May. Seedlings were recruited from 2·6 % of the black seeds and from 2·8 % of the brown seeds in the soil, and only 0·5 % and 0·4 % of the total number of black and brown seeds in the soil, respectively, gave rise to seedlings that survived to produce seeds. Salinity and water stress induced dormancy in black seeds and decreased viability of brown seeds. Brown seeds formed only a transient soil seed bank and black seeds a persistent seed bank.

Conclusions

The presence of a dormancy cycle in black but not in brown seeds of S. corniculata and differences in germination requirements of the two morphs cause them to differ in their germination dynamics. The study contributes to our limited knowledge of dormancy cycling and seed bank formation in species producing heteromorphic seeds.     

Annuario Della Società Botanica Italiana 1937

Abstract

The European heathers Erica manipuliflora, Erica multiflora and Erica vagans (sect. Gypsocallis) are related species characterized by a glabrous ovary, exerted, muticous anthers and a pale pink, urceolate corolla. The existence of three species is the most accepted treatment for this group, but there are uncertainties about this taxonomic interpretation. In this article, we used seed morphological characters to assess the systematics of the group. Seeds were studied by means of scanning electron microscopy techniques. E. multiflora has a distinct seed type, 1–1.5 mm long, flattened, yellowish with a striate-reticulate primary sculpture. E. vagans and E. manipuliflora have smaller seeds, brown with a reticulate pattern. Seeds of E. vagans are globose, 0.5 mm wide, while E. manipuliflora has mostly ellipsoid seeds 0.7 mm long. However, seeds of E. manipuliflora from the Adriatic coasts are closer to those of E. vagans, and this may support the existence of E. manipuliflora subsp. anthura.     

Seed germination and seedling physiology of Larix kaempferi and Pinus densiflora in seedbeds with charcoal and elevated CO2

We investigated the effect of ectomycorrhizal colonization, charcoal and CO₂ levels on the germination of seeds of Larix kaempferi and Pinus densiflora, and also their subsequent physiological activity and growth. The seeds were sown in brown forest soil or brown forest soil mixed with charcoal, at ambient CO₂ (360 μmol mol⁻¹) or elevated CO₂ (720 μmol mol⁻¹), with or without ectomycorrhiza. The proportions of both conifer seeds that germinated in forest soil mixed with charcoal were significantly greater than for seeds sown in forest soil grown at each CO₂ level (P < 0.05; t-test). However, the ectomycorrhizal colonization rate of each species grown in brown forest soil mixed with charcoal was significantly lower than in forest soil at each CO₂ treatment [CO₂] (P < 0.01; t-test). The phosphorus concentrations in needles of each seedling colonized with ectomycorrhiza and grown in forest soil were greater than in nonectomycorrhizal seedlings at each CO₂ level, especially for L. kaempferi seedlings (P < 0.05; t-test), but the concentrations in seedlings grown in brown forest soil mixed with charcoal were not increased at any CO₂ level. Moreover, the maximum net photosynthetic rate of each seedling for light and CO₂ saturation (P _max) increased when the seedlings were grown with ectomycorrhiza at 720 μmol mol⁻¹ [CO₂]. Ectomycorrhizal colonization led to an increase in the stem diameter of each species grown in each soil treatment at each CO₂ level. However, charcoal slowed the initial growth of both species of seedling, constraining ectomycorrhizal development. These results indicate that charcoal strongly assists seed germination and physiological activity.     

Fruit diet of Alouatta guariba and Brachyteles arachnoides in Southeastern Brazil: comparison of fruit type, color, and seed size

Fruit is an important food resource for neotropical primates. In this study I compare the fruit diet of sympatric brown howlers (Alouatta guariba) and southern muriquis (Brachyteles arachnoides). Feeding behavior was studied over 12 months and fruit species consumed were identified and assigned to the categories fruit type, fruit color, and seed size. Observed-fruit feeding records were compared with expected records determined from local availability of the fruit of the tree species. I also determined dietary overlap. Fruit consumption occupied 8 and 12% of the feeding time of A. guariba and B. arachnoides, respectively. Fruit from eight tree species were consumed by the former and fruit from twenty-two species by the latter. Patterns of fruit selection of A. guariba and B. arachnoides varied widely. Although howlers and muriquis converge behaviorally by selecting fruit with common attributes (fleshy/unprotected, violet and brown/black-colored), unlike A. guariba, B. arachnoides fed on immature seeds of fleshy/protected and dry fruit. Large seeds were ingested, and defecated intact, by B. arachnoides only. There was little overlap of fruit diet even within categories that had been selected by both, suggesting that dietary divergence is occurring at the interspecific level. Different resource exploitation probably mediates the coexistence of A. guariba and B. arachnoides in low diversity, semideciduous forests, where the environment imposes narrow limits on primate food choices.     

Bimodal colour pattern of individual Pinus halepensis Mill. seeds: a new type of crypsis

Variation in seed traits is a well‐known phenomenon affecting plant ecology and evolution. Here we describe, for the first time, a bimodal colour pattern of individual seeds, proposing an adaptive explanation, using Pinus halepensis as a model. Pinus halepensis disperses its seeds either by wind on hot dry days, from regular cones, or after fires, mainly from serotinous cones. Post‐dispersal seeds are exposed to strong predation by passerine birds, making crypsis important for seed survival. Individual seeds from non‐serotinous cones have a bimodal colour pattern: one side is light brown and the other black, exposing only one colour when lying on the ground. Serotinous cones from most trees have seeds with similar bimodal colour patterns, whereas seeds from serotinous cones of some trees are light brown on both sides. The dark side provides the seed with better crypsis on dark soils, whereas the light‐brown side is better adapted to light‐coloured soils, and mainly to light‐grey ash‐covered soil, which is the natural post‐fire regeneration niche of P. halepensis. The relative reflection curves of the black and brown seed colours differ, and their calculated relative chromatic distance is 5: meaning that seed‐predating passerine birds see them differently, and probably prefer seeds that present a higher contrast against the soil background. We propose that such a bimodal colour pattern of individual seeds is probably an overlooked general phenomenon mainly linked to seed dispersal in post‐fire and other heterogeneous environments. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 271–278.     

Effect ofAspergillus parasiticus soil inoculum on invasion of peanut seeds

Environmental control plots adjusted to late season drought and elevated soil temperatures where inoculated at peanut planting with low and high levels of conidia, sclerotia, and mycelium from a brown conidial mutant ofAspergillus parasiticus. Percentage infection of peanut seeds from undamaged pods was greatest for the subplot containing the high sclerotial inoculum (15/cm² soil surface). Sclerotia did not germinate sporogenically and may have invaded seeds through mycelium. In contrast, the mycelial inoculum (colonized peanut seed particles) released large numbers of conidia into soil. Soil conidial populations of brownA. parasiticus from treatments with conidia and mycelium were positively correlated with the incidence of seed infection in undamaged pods. The ratio ofA. flavus to wild-typeA. parasiticus in soil shifted from 7:3 to 1:1 in the uninoculated subplot after instigation of drought, whereas in all subplots treated with brownA. parasiticus, the ratio of the two species became approximately 8:2. Despite high levels of brownA. parasiticus populations in soil, nativeA. flavus often dominated peanut seeds, suggesting that it is a more aggressive species. Sclerotia of wild-typeA. parasiticus formed infrequently on preharvest peanut seeds from insect-damaged pods.     

Comparative Seed Dispersal Effectiveness of Sympatric Alouatta guariba and Brachyteles arachnoides in Southeastern Brazil1

I compared the effectiveness of sympatric brown howlers (Alouatta guariba) and muriquis (Brachyteles arachnoides) as seed dispersers in terms of quantitative and qualitative attributes. I hypothesized that differences in feeding and behavioral patterns between these large‐bodied folivorous/frugivorous primates would lead to dissimilarities in their effectiveness as endozoochoric seed dispersal agents. The study was carried out in a semideciduous forest fragment of Fazenda Barreiro Rico, southeastern Brazil. Through behavioral sampling of frugivory and defecation events as well as analyses of fecal samples, I determined that A. guariba dispersed fewer species and produced a lower proportion of dung with intact seeds than B. arachnoides. There was no difference between the number of seeds in fecal samples of A. guariba and B. arachnoides. These primates affected to a similar degree both germination percentage and latency to germination of seeds they ingested or removed the pulp from. Howlers and muriquis were also similar in carrying seeds away from the parent trees. Contrary to muriquis, howlers defecated seeds under the canopy of conspecific lianas, where seeds are expected to suffer high mortality rates, and voided seeds predominantly in a clumped pattern. B. arachnoides was a more effective seed disperser when compared to A. guariba in some attributes evaluated, but not in others. Given the interspecific variation in recruitment patterns of tropical plants and the loss of frugivorous bird species at the study site, the differences between howlers and muriquis in their abilities as seed dispersers may crucially influence the composition and maintenance of seedling diversity.     

Seed macro and micro morphology of the selected <Emphasis Type="Italic">Nigella</Emphasis> (Ranunculaceae) taxa from Turkey and their systematic significance

Macro and micromorphological properties of intact and mature seeds of 12 taxa (species and varieties) belonging to Nigella L. (Ranunculaceae) was investigated using light and scanning electron microscopy. Material studied covers 11 species of 15 Turkish Nigella. Studied taxa were divided into two types. Type I has ovate to orbicular seeds that includes four species. Type II has triquedrous seeds and includes seven species. Type II was subdivided into two. Type IIa has triquedrous to subpyramidal seeds (five species) and Type IIb has triquedrous to subglobose seeds (two species). Further segregation was performed micromorphologically and an identification key of studied Nigella taxa was given. Studied Nigella taxa have a diverse macro and micromorphological characters that utilize to separate them from each other to assess the systematics of Nigella.     

Effects of germination time on seed morph ratio in a seed-dimorphic species and possible ecological significance

Background and Aims Diaspores of heteromorphic species may germinate at different times due to distinct dormancy-breaking and germination requirements, and this difference can influence life history traits. The primary aim of this study was to determine the effect of germination time of the two seed morphs of Suaeda corniculata subsp. mongolica on life history traits of the offspring.Methods Germinated brown and black seeds were sown on the 20th of each month from April to September in a simulated but near-natural habitat of the species. Phenological and vegetative traits of the maternal plants, and number, size and germination percentage of the offspring were determined.Key Results Germinated seeds sown late in the year produced smaller plants that had a higher proportion of non-dormant brown than dormant black seeds, and these brown seeds were larger than those produced by germinated seeds sown early in the year. The length of the seedling stage for brown seeds was shorter than that for black seeds, and the root/shoot ratio and reproductive allocation of plants from brown seeds were more variable than they were for plants from black seeds. Late-germinating brown seeds produced larger plants than late-germinating black seeds.Conclusions Altering the proportion of the two seed types in response to germination timing can help alleviate the adverse effects of delayed germination. The flexible strategy of a species, such as S. corniculata, that produces different proportions of dimorphic seeds in response to variation in germination timing may favour the maintenance and regeneration of the population in its unpredictable environment.     

Eriocaulon vandaanamense sp. nov. (Eriocaulaceae) from Kerala,India

Eriocaulon vandaanamense (Eriocaulaceae), a new species from a marshy coastal area in the Alappuzha District, Kerala, India, is described and illustrated. The new species is similar to E. truncatum and resembles it in having vertically elongated seed coat cells, but differs mainly in having pale black hoary floral bracts, 3‐lobed hoary male sepals, linear‐falcate, non‐conduplicate hoary female sepals, and small, smooth, pale brown seeds without seed coat appendages.