DIFFERENTIAL LIFE HISTORY PHASE EXPRESSION IN TWO COEXISTING SPECIES OF SCYTOSIPHON (PHAEOPHYCEAE) IN NORTHERN CHILE1

The identity of two phaeophycean taxa that monopolized the middle‐lower rocky intertidal zone of a coastal area chronically exposed to copper mine wastes in northern Chile was unraveled. One of them was preliminarily identified as the gametophytic stage of Scytosiphon lomentaria (Lyngbye) Link. The other, a dark crust, resembled the alternate stage of some Scytosiphon species. Comparative analysis of morphology, life history, and DNA sequences strongly suggests that crusts corresponded to sporophytic S. tenellus Kogame and confirm that erect thalli belonged to S. lomentaria. A clear segregation of erect and crustose thalli was found using internal transcribed spacer region 1 and RUBISCO spacer sequences. Furthermore, whereas crusts always grouped with S. tenellus, erect thalli always grouped with S. lomentaria. Life history studies failed to connect the two entities. First, field‐collected S. tenellus produced progeny that either recycled the crust, which reproduced by unilocular zoidangia, or developed into erect thalli. The latter, unlike typical gametophytic S. lomentaria, developed patchy sori of plurilocular zoidangia. Second, S. lomentaria displayed a direct‐type life cycle, in which progeny from erect individuals only developed into erect thalli and produced only plurilocular zoidangia. This constitutes the first experimental study on Scytosiphon from the Pacific coast of South America and the first report of S. tenellus on this coast. It is also the first report of the crustose stage of Scytosiphon appearing as a perennial and dominant algal species in a temperate rocky intertidal system.     

Polysiphonia perforans sp. nova (Ceramiales,Rhodophyta) from the Mediterranean Sea

ABSTRACT

A new species of the genus Polysiphonia from the Mediterranean Sea is described. It is an ecorticate species, with 4 pericentral cells, showing prostrate axes from which erect axes arise. Rhizoids are formed by pericentral cells in a median position remaining in open connection with them. Erect axes are straight, simple throughout or pseudodichotomous at the base then simple or with one (rarely two-three) orders of branching; trichoblasts and scar cells not observed. Only tetrasporangial plants were found. They show ellipsoid tetrasporangia borne in short straight series, often interrupted by sterile segments. The new species is also characterized by a peculiar habit consisting of prostrate axes, adhering to lower faces of Peyssonnelia spp. by means of rhizoids growing upward, from which erect upright axes perforating thalli of the supporting species arise. A comparison with the related species of Polysiphonia was also carried out.     

Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidagocanadensis and S. gigantea)

The two rhizomatous perennials Solidago canadensis and S. gigantea belong to the most widespread alien plants in Europe. Anecdotal observations suggest that they disperse also by rhizome fragments. For testing their resprouting ability, rhizome fragments of different sizes from both species were buried at four different soil depths (0, 5, 10 and 20 cm, respectively) in a common garden. Rhizome fragments of S. canadensis ranged 3–6 cm in length, those of S. gigantea 5–20 cm in length. Resprouting plants were harvested after 3 months and growth related traits measured to assess their vitality. Resprouting rate in S. gigantea was far higher than in S. canadensis (85 and 19%, respectively). In S. gigantea, fragments of all sizes resprouted from all soil depths whereas none rhizome of S. canadensis emerged from 20 cm burial depth. In S. gigantea, size related traits showed significant interactions between fragment size and burial depth, but not relative shoot growth rate. At all burial depths, vitality of plants emerging from small rhizomes was lower than plants emerging from large rhizomes. Effects of rhizome size became stronger with increasing burial depth. The results show that both species are able to resprout from buried rhizome fragments, and that succesful regeneration is more likely to occur in S. gigantea. Managing these species should avoid any activities promoting rhizome fragmentation and dispersal of fragments.     

Fine-scale dynamics of rhizomes in a grassland community

Spatial dynamics in grassland communities are constrained by the belowground spatial distribution of roots and rhizomes. Their dynamics are difficult to measure as underground data collection tends to be destructive and cannot be repeated at the same plot over time. We investigated rhizome dynamics indirectly by examining rhizome spatial structure on long‐term grassland study plots where aboveground shoot counts have been recorded using a fine‐scale grid over nine years. Number of rhizome apical ends, basal ends and total rhizome length of both live and dead rhizomes were obtained from the data by scanning rhizomes and processing them by GIS vectorization. These rhizome variables were correlated with the above‐ground shoot counts in grid cells over varying temporal lags. There was a general decrease in the intensity of correlation between live rhizomes and shoot counts with increasing time lags. Correlation of dead rhizomes increased with increasing time lag, reaching a maximum after several years, and then declined. Species differed strongly in the change of rhizome‐shoot counts correlation over varying time lags. These differences were used to infer rhizome growth dynamics, namely rhizome growth rate and lifespan, and rhizome mean decomposition time. The species involved differed in all these traits. Mean rhizome growth rate ranged from 0.2 (Polygonum bistorta) to 3.3 cm ur^?1 (Deschampsia flexuosa); mean rhizome lifespan ranged from 5 yr (Anthoxanthum alpinum) to over 8 yr (Nardus stricta) and mean decomposition time from one growing season (Anthoxanthum) to 7 yr (Polygonum). Presence of dead rhizomes below living rhizomes or aboveground shoots was taken as an indication of fine‐scale replacements between species. These were highly non‐random, with some species pairs replacing significantly more frequently. These differences in rhizome growth parameters underlie different strategies of horizontal growth and dieback between species. These can serve as one of the mechanisms of species replacements and contribute to the fine‐scale coexistence of species.     

Caesia sabulosa (Hemerocallidaceae), a new species from the Greater Cape Region of South Africa

The new species Caesia sabulosa Boatwr. and J.C.Manning from deep sands along the West Coast of South Africa and sandy flats in the Cederberg and Bokkeveld Escarpment is described. It is distinguished by its extensively branched rhizome resulting in a robust, clump-forming habit, and unique ‘palisade’ root system of closely packed, hard, vertical roots; mostly larger flowers; erect fruiting pedicels; and details of the seed testa sculpturing.     

Verosphacela silvae sp. nov. (Onslowiaceae, Phaeophyceae) from the Mediterranean Sea

We describe Verosphacela silvae sp. nov., from the Mediterranean Sea. It consists of horizontal filaments living on the lower face of the red alga Peyssonnelia rubra (Greville) J. Agardh, from which erect filaments up to 1.5 mm high rise and grow upright after passing through the thallus of the supporting species. There are both horizontal and erect filaments growing by apical cells. In the subapical cells, 1–2 longitudinal divisions occur (more frequently in the erect filaments) but no secondary transverse divisions occur. Erect filaments bear lateral propagules on a stalk of one to three (rarely more) cells. Propagules, with neither apical cells nor arms, consist of seven cells. Zoidangia are borne at the apex of erect laterals. The new species differs from V. ebrachia Henry mainly in habit, propagules and zoidangia. In addition, distinct from V. ebrachia, filaments of V. silvae never penetrate between the cuticle and the cell wall of the supporting alga. Moreover, propagules of V. silvae consist of seven cells, whereas those of V. ebrachia consist of 9–13 cells, and zoidangia are terminal on laterals in V. silvae, whereas in V. ebrachia they are sessile on both axes and laterals.     

Tinocladia sanrikuensis sp. nov. (Ectocarpales s.l., Phaeophyceae) from Japan

The new species Tinocladia sanrikuensis sp. nov. H.Kawai, K.Takeuchi & T.Hanyuda (Ectocarpales s.l., Phaeophyceae) is described from the Pacific coast of the Tohoku region, northern Japan based on morphology and DNA sequences. The species is a spring–summer annual growing on lower intertidal to upper subtidal rocks and cobbles on relatively protected sites. T. sanrikuensis has a slimy, cylindrical, multiaxial erect thallus, slightly hollow when fully developed, branching once to twice, and resembles T. crassa in gross morphology. The erect thalli are composed of a dense medullary layer, long subcortical filaments, and assimilatory filaments of 11–35 cells, up to 425 μm long and curved in the upper portion. Unilocular zoidangia are formed on the basal part of assimilatory filaments. The species is genetically most closely related to T. crassa and has the same basic thallus structures but differs in having thinner and longer assimilatory filaments. DNA sequences of the mitochondrial cox1 and cox3, chloroplast atpB, psaA, psbA and rbcL genes support the distinctness of this species.     

Life histories of Colpomenia sinuosa and Hydroclathrus clathratus (Scytosiphonaceae, Phaeophyceae) in culture

Life-history studies in culture were carried out on Colpomenia sinuosa (Mertens ex Roth) Derbès et Solier and Hydroclathrus clathratus (C. Agardh) Howe (Scytosiphonales, Phaeophyceae) from Japan. These species showed a heteromorphic life-history pattern with an alternation between erect thalli bearing plurilocular zoidangia and prostrate thalli bearing ectocarpoid plurilocular and unilocular zoidangia. Plurizoids released from erect and prostrate thalli developed into prostrate thalli. Unizoids, however, developed into erect thalli. Prostrate thalli produced plurilocular zoidangia in long-day conditions and unilocular zoidangia in short-day conditions at 10-20°C. Prostrate thalli of C. sinuosa formed ascocysts. Germlings of both species did not grow at 5°C.     

Structure of Adnate Colony Portions in Crisiidae (Bryozoa Cyclostomata)

The “rhizoidsrdquo; surrounding the base of the erect “colony” emanating from the ancestrula in the Crisiidae, especially the simple species Crisidia cornuta (L.), are a regular adnate system of autozooids. Each autozooid is composed of a proximal adnate part and a distal peristome (in some species kenozooids are possibly intercalated). The autozooid peristomes support erect branches identical in budding and structure with the branch emanating from the erect peristome of the ancestrula. Thus, the complete crisiid colony consists of an adnate system of ancestrula and autozooids, which form erect branches from their peristomes. The adnate zooid system is comparable in autozooid morphology and budding pattern with simple uniserial stomatoporids. The tentative hypothesis is proposed that the crisiid group has developed from primitive stomatoporids; the adnate zooid system of the stomatoporids apparently evolved peristomial budding to produce the erect colony branches characteristic of crisiids.     

Hoya amicabilis sp. nov. (Apocynaceae,Asclepiadoideae), from Java discovered on Facebook

A new species from Java, Hoya amicabilis S.Rahayu & Rodda is described and illustrated. It was first identified as a new species from pictures posted on social media in 2017. Hoya amicabilis is part of a small group of species that have an unusual shrubby habit, but it is the only one in that group with bright yellow campanulate flowers. Furthermore, Hoya amicabilis is a rather unusual species of Hoya since its staminal corona lobes are oblong, erect, while most species of Hoya have well‐developed generally spreading corona lobes, and its style head is umbonate, brightly coloured and extending above the anther appendages, while most species have a conical style head covered by anther appendages.     

Do rhizome severing and shoot defoliation affect clonal growth of Leymus chinensis at ramet population level?

Leymus chinensis (Trin.) Tzvel. is a perennial species of Gramineae, usually subject to defoliation from grazing and mowing. We examined whether shoot defoliation and rhizome severing affected rhizome and ramet growth, and vegetative bud outgrowth of L. chinensis ramet populations. We also tested the hypothesis that clonal growth of the ramets subject to defoliation would benefit from clonal integration between interconnected ramets besides from possible compensatory growth. To 48 experimental plots, we applied six treatments resulting from interactions between two rhizome connection states (unsevered/severed) and three defoliation regimes (non-defoliated, mildly-defoliated and heavily-defoliated). Defoliation affected rhizome growth and bud outgrowth, but had little effect on shoot growth. Mild and heavy defoliation exerted similar effects on rhizome growth. Only heavy defoliation significantly reduced bud outgrowth while mild defoliation did not. The fact that shoot growth did not change after defoliation and that the bud numbers remained unchanged after mild defoliation suggest that the compensatory response enable the species to tolerate grazing to some extent. Neither rhizome severing nor the interaction of rhizome severing and defoliation had effect on any tested variables. Lack of the effect of rhizome severing falsified the first half of our hypothesis, that is, clonal integration was unimportant in our experiment. The probable reasons were suspected to be the short duration of the experiment and/or the buffer effect of carbohydrate reserves in rhizomes for shoot growth and bud production in time of defoliation.     

长期淹水对河竹鞭根养分化学计量特征的影响

以长期淹水环境下能生长更新的河竹为材料,调查测定了人工喷灌供水(CK)、淹水6个月(TR)的河竹一年生竹鞭的根生物量和主要养分元素含量,分析长期淹水对河竹鞭根养分化学计量特征的影响,为河竹在水湿地和消落带植被恢复中的应用提供理论依据。结果显示:(1)与CK相比,TR处理下的河竹土中根的N、P、Mg和Ca含量显著降低,Fe含量显著升高,且N、K和Ca含量显著低于TR处理下水中根的含量,而Fe含量显著高于水中根。(2)TR处理的河竹土中根的C/N、C/P、C/K和P/K较CK显著升高,且C/K、N/K和P/K显著高于TR处理的水中根。(3)TR处理的河竹水中根的C-N、C-P、N-P均呈极显著正相关关系,土中根的C-P、C-K、P-K均呈极显著正相关关系;CK河竹土中根的C-P、C-K呈极显著正相关关系,且N-P显著相关;从相关系数看,TR处理下土中根的C-N、N-P和N-K相关性减弱,C-P、C-K和P-K相关性增强,而C-N、C-P、N-P和N-K相关性较水中根减弱,C-K和P-K相关性较水中根增强。(4)TR处理下鞭根生物量和C、N、P、K、Mg、Ca积累量较CK分别显著降低19.46%、42.04%、36.55%、41.39%、60.06%和38.46%,而Fe积累量显著升高,为CK的5.5倍;TR处理下土中根养分积累量显著高于水中根。研究表明,长期淹水虽阻碍了河竹鞭根的养分平衡吸收,但能够提高养分利用效率,并且土中根和水中根具有克隆分工特征,水中根主要起到氧气吸收应对缺氧环境胁迫的功能,是河竹适应长期淹水环境的重要生态对策。     

Life history of Japanese Stypocaulon durum (Sphacelariales, Phaeophyceae)

Phenology, morphology, life history and responses to different temperature and photoperiod conditions were studied in Japanese Stypocaulon durum (Ruprecht) Okamura. Erect thalli of the species were collected year-round, but the mature thalli forming either uniloc-ular sporangia or two different types of plurilocular structures (evidently gametangia) on separate thalli were found only in winter. ln culture, an isomorphic life history is suggested for the species, alternating between a sporophyte forming unilocular sporangia and gam-etophytes forming plurilocular macro- (female) and micro- (male) gametangia. Contents of unilocular sporangia were not released, but germinated in situ, developing into erect thalli forming plurilocular gametangia. Macrogametangia released aplanogametes (oospores), but male gametangia appeared to be non-functional, although flagellated cells were once formed in the loc-uli. This is the first report of plurilocular gametangia in the species. Although the species grew well and matured under considerably lower temperature conditions than European Stypocaulon scoparium (L.) Sauvageau, its temperature requirements showed similarity to northwestern Atlantic Stypocaulon species. This supports the notion that northwestern Atlantic Stypocaulon is conspecific with S. durum.     

THE VEGETATIVE ANATOMY OF JAUMEA CARNOSA (LESS.) GRAY (ASTERACEAE), A SALT MARSH SPECIES

Certain anatomical characters of Jaumea carnosa, a salt marsh plant, which are diagnostic, adaptive, or otherwise important for an ecological anatomy study are described. The characters which follow are noteworthy. The plant has a sympodial construction forming an extensively branched rhizome system, and erect lateral shoots which eventually become prostrate. The leaves have very few, and only moderately developed succulent characters, such as: poorly defined palisade tissue, central mesophyll cells which are slightly enlarged anticlinally, and a complete lack of sclerification in the mesophyll. A continuous schizogenous canal system lined with epithelial cells lies in the ground tissues of all stem forms and leaves. The phellem is composed of thin-walled, only lightly suberized cells. Very broad parenchymatous areas develop in the secondary tissues of the rhizome, associated with a slowing of vascular cambial activity which creates depressions in the axis. Adventitious roots arise from ground tissues close to the primary xylem and from interfasicular regions close to the primary phloem in the rhizomes.     

Hormonal control of the outgrowth of axillary buds in <Emphasis Type="Italic">Alstroemeria</Emphasis> cultured <Emphasis Type="Italic">in vitro</Emphasis>

We study apical dominance in Alstroemeria, a plant with an architecture very different from the model species used in research on apical dominance. The standard explant was a rhizome with a tip and two vertically growing shoots from which the larger part had been excised leaving ca. 1 cm stem. The axillary buds that resumed growth were located at this 1-cm stem just above the rhizome. They were released by removal of the rhizome tip and the shoot tips. Replacement of excised tips by lanolin with indole-3-butyric acid (IBA) restored apical dominance. The auxin transport inhibitors 2,3,5-triiodobenzoic acid (TIBA) and N-1-napthylphthalamic acid (NPA) reduced apical dominance. 6-Benzylaminopurine (BAP) enhanced axillary bud outgrowth but the highest concentrations (> 9 μM) caused fasciation. Thidiazuron (TDZ) did not show improvement relative to BAP. Even though the architecture of Alstroemeria and the model species are very different, their hormonal mechanisms in apical dominance are for the greater part very similar.     

Comparison of light harvesting and resource allocation strategies between two rhizomatous herbaceous species inhabiting deciduous forests

Light conditions on the floor of deciduous forests are determined by the leaf dynamics of canopy trees and gap formation. Such spatiotemporal variations of light availability should affect the resource partitioning strategies of understory herbs. Although rhizomatous species are common in understory, relationships between rhizome structure, vegetative growth, and sexual reproduction are unclear in terms of carbon allocation. We compared the photosynthetic characteristics and carbon translocation patterns in the under-canopy and light-gap sites between two summer-green perennial species: Cardamine leucantha with an annual long rhizome, and Smilacina japonica with a perennial short rhizome system. Flowering of both species occurs in early summer under decreasing light availability. In the light-gap, C. leucantha maintained high photosynthetic activity due to continuous leaf production, resulting in higher seed production than in the under-canopy. In contrast, the photosynthetic rate of S. japonica, producing leaves simultaneously, decreased with time irrespective of light conditions, resulting in stable seed production in both sites. Although seasonally decreasing light availability commonly restricts carbon assimilation of understory herbs, the responses of resource partitioning to variations in light availability depend greatly on the belowground structure of individual species.     

Micropropagation of Ranunculus Asiaticus: A Review and Perspectives

Ranunculus asiaticus is an important ornamental species mainly cultivated in the countries surrounding the Mediterranean sea. So far the multiplication of this plant has been mainly carried out by seed and rhizome division; however, these systems present many drawbacks. Tissue culture is an attractive alternative for accelerated propagation of selected and indexed genotypes. In this paper we review the work carried out on in vitro culture of R. asiaticus and present a flow chart for its commercial production, using axillary budding and embryogenesis. Although the price of micropropagated plants is higher compared to traditional material (seedlings and rhizomes from seed populations), it should be considered that tissue cultured plants have a better rhizome yield per plant; moreover, the tissue culture approach allows to offer clonal material of selected lines.     

Studies in African Cyperaceae 30. Hypolytrum subcompositus, sp. nov.

A new species to science, Hypolytrum subcompositus is described from Kodmin in South West Cameroon. The species is distinct from other African species and appears to have no close relatives. It is a fairly large perennial with a short erect rhizome with many crowded leaves at its end, and (below the leaves) 1–3 lateral culms carrying reduced leaves and a terminal cinnamon-whitish rather congested inflorescence.     

Osservazioni sulla polistelia in Primula glaucescens Moretti e Primula longobarda Porta

Abstract

Notes on the polystelic structure in Primula glaucescens Moretti and Primula longobarda Porta. — The rhizome anatomy of Primula glaucescens Moretti and Primula longobarda Porta (two species endemic to Lombardy) have been studied. It has been found that the polystelic structure is present in the rhizome of both species, but with some differences. The taxa show a difference in the number and size of steles and amount of sclerenchymatic tissue within the single stele.

Our investigations confirm the necessity to separate in a specific rank Primula glaucescens Moretti from Primula longobarda Porta, as already proposed by Arietti and Crescini (1976).