Geophyte Species Research Articles

In Vitro Micropropagation of the Vulnerable Chilean Endemic Alstroemeria pelegrina L.

The Chilean rhizomatous geophyte Alstroemeria pelegrina (A. pelegrina), a species endemic to the Coquimbo (31°45′ S) and Valparaíso (33°12′ S) regions, is currently classified as vulnerable and experiencing population decline due to loss of habitat. This heightened threat underscores the need to develop effective mass propagation techniques to support its conservation efforts. Consequently, the present study aimed to establish an optimized in vitro propagation protocol tailored specifically for A. pelegrina to facilitate its large-scale propagation and promote the preservation of this vulnerable geophyte. In our experiment, explants obtained from in vitro germination were used. These explants were then cultured on a Murashige and Skoog (MS) medium solidified with agar (6 g L−1) and supplemented with 2.22 μM 6-Benzylaminopurine (BAP) and 30 g L−1 sucrose. The results indicated an average of 4.6 new shoots produced per initial explant. The implementation of light-emitting diode (LED) illumination with a red:blue ratio of 3:1 and 2.22 μM BAP resulted in an average shoot length of 6.2 cm. For rhizome induction, the addition of either 5.37 μM 1-naphthaleneacetic acid (NAA) or 5.37 μM indole-3-butyric acid (IBA) resulted in average rhizome lengths of 1.9 cm and 1.7 cm, respectively, with fresh weights of the vitroplants ranging from 2.9 g to 3.1 g, and rooting percentages between 100% and 96%, respectively. Notably, the survival rate of rooted plants obtained through in vitro propagation was 90% after a 4-week acclimatization period in a cold greenhouse, indicating the efficacy of the developed protocol for mass propagation and conservation efforts of this vulnerable geophyte species.

A Review on Flower Bulb Micropropagation: Challenges and Opportunities

This comprehensive review scrutinizes tissue culture and micropropagation methodologies in geophytes, focusing on bulbous plants. The examination encompasses key stages, including somatic embryogenesis, bulb growth, dormancy breaking, and planting. Studies underscore the pivotal role of plant growth regulators (PGRs) in plant regeneration and bulb growth. Bioreactor systems for healthy plant regeneration, rooting methods, acclimatization strategies, and considerations for ex vitro survival are elucidated. The review also delves into somaclonal variation dynamics and acknowledges the burgeoning field of gene editing, particularly Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) studies, as a promising avenue for enhancing valuable compound content in geophytes. In addition to addressing challenges in flower bulb micropropagation, this review briefly highlights emerging opportunities, including the potential integration of artificial intelligence (AI) to optimize culture conditions, predict growth parameters, and enhance efficiency in bulb production. The conclusion emphasizes the necessity of a multifaceted approach integrating biochemistry, physiology, and molecular biology to address existing challenges and improve tissue culture protocols for diverse geophyte species. This review article also intends to highlight how tissue culture techniques could contribute to the development and valorization of flower bulbs in today’s scenario of the ornamental industry.

Resource availability and disturbance frequency shape evolution of plant life formsin Neotropical habitats.

Organisms use diverse strategies to thrive in varying habitats. While life history theory partly explains these relationships, the combined impact of resource availability and disturbance frequency on life form strategy evolution has received limited attention. We use Chamaecrista species, a legume plant lineage with a high diversity of plant life forms in the Neotropics, and employ ecological niche modeling and comparative phylogenetic methods to examine the correlated evolution of plant life forms and environmental niches. Chamaephytes and phanerophytes have optima in environments characterized by moderate water and nutrient availability coupled with infrequent fire disturbances. By contrast, annual plants thrive in environments with scarce water and nutrients, alongside frequent fire disturbances. Similarly, geophyte species also show increased resistance to frequent fire disturbances, although they thrive in resource-rich environments. Our findings shed light on the evolution of plant strategies along environmental gradients, highlighting that annuals and geophytes respond differently to high incidences of fire disturbances, with one enduring it as seeds in a resource-limited habitat and the other relying on reserves and root resprouting systems in resource-abundant habitats. Furthermore, it deepens our understanding of how organisms evolve associated with their habitats, emphasizing a constraint posed by low-resource and high-disturbance environments.

Can ploidy levels explain the variation of Herbertia lahue (Iridaceae)?

Polyploidy is often related with phenotypic variation, as observed in Herbertia lahue, a geophyte species. This study examined the H. lahue polyploid series and departure in cytogenetic, morphometric, and pollen data. Diploids (2n=2x=14) present bimodal karyotype with two long and five short chromosome pairs, while hexaploids (2n=6x=42) and octoploids (2n=8x=56) present a gradual decrease in chromosome size. All cytotypes have CMA+/DAPI- bands co-localized with 18S rDNA sites in the satellite region (no DAPI+ bands in any cytotype). Unlike diploids and octoploids, 5S rDNA interstitial sites in hexaploids are not in a syntenic position with 18S rDNA sites. Genome size is effective as an indirect predictor of the cytotypes since 2C-values increased according to ploidy level. The reduction in the number of the rDNA sites in polyploids associated with their lower 1Cx-values compared to diploids may suggest a genome downsizing process. Morphometric analysis revealed significant differences among cytotypes, and discriminant analysis identified three morphometric groupings corresponding to the cytotypes. The phenotypic variation observed in pollen grains, bulbs, and ovary characters suggested the gigas effect. Concluding, remarkable differentiation was observed at both genomic and phenotypic characters in all the cytotypes analyzed, suggesting a possible ongoing speciation process in H. lahue.

Ancient agricultural terrace walls control floods and regulate the distribution of Asphodelus ramosus geophytes in the Israeli arid Negev

Ancient stone terrace walls aimed at harvesting water runoff and facilitating crop production are widespread across the drylands of the Middle East and beyond. In addition to retaining the scarce water resource, the terrace walls also conserve soil and thicken its profile along ephemeral stream channels (wadis) by decreasing fluvial connectivity and mitigating erosional processes. In this study, we created hydrological models for three wadis with ancient stone terrace walls in the arid northern Negev of Israel, where the predominant geophyte species is Asphodelus ramosus L. A two-dimensional (2D) rain-on-grid (RoG) approach with a resolution of 2 m was used to simulate the rain events with return periods of 10, 20, 50, and 99 % (10-y, 5-y, 2-y, and yearly, respectively) based on the Intensity-Duration-Frequency rain curves for the region. To evaluate the effect of stone terrace walls on fluvial hydrology and geomorphology, the ground level was artificially elevated by 20 cm at the wall locations in a digital terrain model (DTM), using the built-in HEC-RAS 2D terrain modification tool. Our results showed that the terraced wadis have a high capacity to mitigate runoff loss, but a lesser capacity to delay the peak flow. Yet, for all rainstorm return periods, peak flow mitigation was positively related to the number of terrace walls along the stream channel. Field surveys in two of the studied wadis demonstrated that the A. ramosus clones were found in proximity to the stone terrace walls, presumably due to the greater soil–water content there. The results thus suggest that the terrace walls provide improved habitat conditions for these geophytes, supporting their growth and regulating their distribution along the wadi beds.

A mowing strategy for urban parks to support spring flowers in a mediterranean climate city in South Africa

Converting road verges and Public Open Space (POS) to floral-rich resources is an important strategy for supporting populations of urban pollinators. One of the ways this can be achieved is through adjusting mowing schedules, either with a “delayed start” after the end of winter, or a reduction in mowing frequency. In Mediterranean climate ecosystems with mild, wet winters, plant growth continues through the winter season and the definition of a “delayed start” is unclear. This study sought to identify a strategic period for the suspension of mowing activities in a city in South Africa with a Mediterranean climate. It estimated the duration of the flowering to seed-broadcast season of 20 species of native geophytes. Observations were made of phenological status from bud to seed broadcast in ten city parks in Cape Town during the austral spring flowering seasons of 2019 and 2020 (August – December). The Underhill and Zucchini (1988) Moult Model was employed to estimate the duration of the flowering season. Model results showed that mowing should stop in the second week of August and should not resume until the beginning of November in the study context. The results are discussed against the relative biodiversity contribution that different parks and verges make and the potential conflicts with the utility objectives of urban society.

Plant Growth Regulators for the Cultivation and Vase Life of Geophyte Flowers and Leaves

Geophytes are a very important group among ornamental plants, for which more and more plant growth regulators (PGRs) are being used to improve the plant quality, flowering intensity, and vase life of flowers and leaves. PGRs constitute a large group of naturally occurring or synthetically produced organic chemical compounds. There are many factors that influence the efficiency of PGRs, and the method of their application plays a key role in determining their success. In the case of geophytes, the most common method of application is spraying and soaking the storage organs before planting. This article presents information on the application of PGRs to different species of geophytes, both at the cultivation stage and during the post-harvest treatment of flowers and leaves.

The Relationship of Plant Types Familia Araceae on The Mountain Sidole Track Central Sulawesi Based on Morphological Character

The Araceae family plant in the Mount Sidole has a diversity and variety of life forms. The purpose of this study is to describe the family relationship of Araceae family based on morphological characters. Sampling using the path method (belt transect) with free collection techniques. The size of the track used is 10 m wide and ± 15 km long along the Sidole Mountain climbing track at an altitude of 400-1780 m above sea level. Morphological data measurement refers to 37 meristic and qualitative characters. Processing data using the File Editor Program (PFE) and analyzed with the Multivariate Statistical Package (MVSP) program. Determination of similarity index with the Simple Matching Coefficient method and kinship between types using the Unweighted Pair-Group Method Using Arithmetic Average (UPGMA). The results of specimen collection are 26 species. Based on the dendrogram of Familia Araceae divided into three groups. Group I are 9 species of hemiepipitic groups which cluster at a coefficient of 76%, namely Amydrium medium, Pothos scandens, Epipendrum sp., Scindapsus treubii, S. pictus, Rhaphidophora sp., R. sylvestris, R. lobbii and R. puberula. Group II are 8 species of geophytes grouping at 77% coefficient, namely Colocasia oresbia, C. esculenta, Xanthosoma violaceumm, X. sagittifolium, Apoballis mutata, Alocasia sp., A. longiloba and A. Macrorrhizos. Group III are 9 species of geophytes grouping at 82% coefficient, namely Spathiphyllum commutatum, Schismatoglottis inculta, S. lancifolia, S. wallichii, S. asperata, S. cadieri, S. calyptrata and S. calyptrata ssp flagelliforme and Aglaonema nitidum.

Toxic and allergenic plant species in primary school yards of Zagreb’s Lower Town district

Abstract The green infrastructure of Zagreb’s Lower Town is made up of row-planted trees and green spaces within blocks of buildings. All schools are surrounded by green spaces that have a positive impact on the environment. Although most green spaces contribute to improving the quality of life, they also contain toxic and allergenic species which are potentially hazardous, particularly to children. This paper aims to make an inventory of plant species in the environment of primary schools in Zagreb’s Lower Town district, and to determine the presence of toxic and allergenic species. The field research was conducted from March to the end of May 2021 at 7 primary school locations. 13 either annual or biennial plant families were catalogued. In total, 34 species of herbaceous perennials and geophytes, and 36 species of trees from 17 plant families were listed. A total of 38 species of shrubs and climbers were found. Also, a total of 35 poisonous and 28 allergenic plant taxa are planted in the green spaces surrounding primary schools. The most common poisonous species found are Hedera helix and Taxus baccata, and Ilex aquifolium, a highly poisonous species, was also found. No moderately poisonous species have been found at all. As far as allergenic species are concerned, school environments are dominated by those that produce low and moderate levels of pollen concentration in the air. Species that produce high levels of pollen concentration (e.g., Betula pendula, Robinia pseudoacacia, etc.) are the least represented ones, while species that produce a very high concentration of pollen have not been recorded in any of the localities.

A Detailed Ecological Exploration of the Distribution Patterns of Wild Poaceae from the Jhelum District (Punjab), Pakistan

The purpose of this study was to investigate the taxonomic diversity, richness, and distribution patterns of Poaceae in relation to abiotic factors in the Jhelum district of the Pakistan Himalayas. We used a random sampling technique from 80 grids within 240 sites with a rich diversity of wild grasses and 720 quadrates in triplets from each site across the Jhelum district between 2019 and 2021 to collect data on grass species and the associated environmental factors and conditions. After evaluating the important value index for each plant taxa and for the environmental data, we analyzed the data using ordination and cluster analysis techniques. Fifty-two Poaceae taxa from twenty-nine genera were recorded within the study area. From a total of 52 recorded Poaceae species, 45 were native and 7 were invasive species. The life form (biological) showed the dominancy of 27 therophyte species, followed by 24 hemicryptophyte species, and 1 geophyte species. Microphyll had the leading leaf size spectra (27 species), followed by nanophyll (12 species), macrophyll (10 species), and leptophyll (3 species). The trend of the life cycle was the maximum (27 spp.) during the monsoon season, followed by spring (11 spp.), winter (8 spp.), and summer (6 spp.). The leading genera were Setaria with 9.61% of the species, followed by Panicum, Cenchrus, and Brachiaria with 7.69% of the species. Aristida and Echinochloa made up 5.76% of the species while Chrysopogon, Digitaria, Eragrostis, Pennisetum, and Poa made up 3.84% of the species. Other genera recorded single species. The leaf size spectra of grasses were dominated by microphylls (50%) followed by nanophylls (23.07%), macrophylls (19.23%), and leptophylls (7.69%). On the basis of the importance value index, the most dominant species was Cynodon dactylon (68), followed by Dichanthium annulatum (58), Brachiaria ramose (38), Dactyloctenium aegyptium (37), Eleusine indica (35), Saccharum bengalense (33), and Cenchrus biflorus (28). Two-way cluster analyses classified the grasses into three plant community associations based on the indicator plant species. Soil parameters as subsamples were tested for moisture, pH, EC, OM, macronutrients (CaCO3, N, P, and K), and saturation while the ordination analysis revealed that they had a significant (p ≤ 0.002) effect on vegetation associations. Overall, this study contributes to a better understanding of the influence of environmental factors on the composition and associations of grass species and the development of scientifically informed management solutions for the ecological restoration of degraded habitats in this Himalayan region.

Ecophysiological and Growth-Related Traits of Two Geophytes Three Years after the Fire Event in Grassland Steppe.

Deliblato Sands is the single largest expanse of sand in Europe. It is the most fire-prone area of Serbia due to the absence of surface water, sandy soils, specific microclimate conditions, and vegetation composition. Post-fire regeneration is a long-term process that includes many aspects of vegetation regrowth and habitat recovery. In the third year following one of the disastrous fires, the growth dynamics of two geophyte species in unburned and burned sites were studied. During the growing season, burned and unburned populations of Crocus reticulatus Steven ex Adam and Iris pumila L. were assessed for growth parameters (biomass production, specific leaf area, leaf area index) and leaf-level ecophysiological traits (photosystem II efficiency, chlorophyll amount, relative water content). Species acclimated differently to changed abiotic and biotic site conditions after the fire event. C. reticulatus burned and unburned populations differed significantly in terms of flowering phenology and ecophysiological traits, whereas I. pumila burned and unburned populations differed significantly in terms of growth parameters. The findings support the assertion that geophytes are generally well adapted to environmental disturbances. Species, however, responded differently to fire-induced changes in the physicochemical and biotic environment, depending on their ecological requirements and adaptive capacity.

A First Study of Urginea maritima Rings: A Case Study from Southern Jordan

Vegetation rings are a common pattern in water-limited environments and mostly occur in clonal plants. This study presents, for the first time, rings of the geophyte species Urginea maritima. The rings, typically 40–90 cm in diameter, are abundant in the sandy environment of Little Petra and Wadi Rum, in the southern Jordanian drylands. Soil properties were studied in the rings’ center, periphery, and matrix. Soil-water volumetric content was significantly higher in the rings’ periphery than in the center and matrix. The soil organic carbon was highest in the periphery, intermediate in the center, and lowest in the matrix. At the same time, the soil texture, hydraulic conductivity, and gravimetric moisture content at the hygroscopic level were similar in the three microenvironments. According to the results, a possible ring formation mechanism is the soil-water uptake mechanism, which results in competition between the plants at the periphery and those in the center and is generally attributed to plants with large lateral root zones. Numerical simulations of a mathematical model implemented in this study support the soil-water uptake mechanism. A second possible mechanism is negative plant-soil feedback due to the accumulation of dead biomass and its consequent decomposition, with the resultant release of autotoxic compounds. It is possible that several mechanisms occur simultaneously and synergistically affect the formation of U. maritima rings.

Determination of carbohydrate accumulation and plant growth dynamics in snowdrop (Galanthus elwesii Hook.) response to moisture levels in different substrates

In terms of botany, geophytes are known by their own survival strategy due to have a swollen storage organs. Snowdrops (Galanthus, 20 spp.; Amaryllidaceae) are important type of wild-sourced ornamental bulb genus in all geophyte species. Also, have a great deal of potential for use on landscape designs. Whereas, not much study has been done regarding the growth dynamics of snowdrops at harsh environmental conditions. This experiment was conducted to evaluate the effects of abiotic stress conditions on the performance of snowdrop (Galanthus elwesii Hook.) in soiless culture. Substrates and moisture were the variables. Peat + perlite and cocopeat were used as a substrate in pots. Moisture levels were applied; ML1, ML2 (well-watered and moderately tolerant treatments), ML3 (moderate stress) and ML4 (severe stress). Moisture had a statistically significant effect (P < 0.05) on circumference size, height and weight of the snowdrop bulbs. Plant height and carbohydrate accumulation were also affected by moisture levels in different substrates. The correlation between total carbohydrate (r = 0.95) and starch (r = 0.98) were positively determined. The reduced sugar, total sugar, starch and total carbohydrate values were increased by the severe stress treatment (ML4).

To Care or Not to Care? Which Factors Influence the Distribution of Early-Flowering Geophytes at the Vienna Central Cemetery (Austria)

Cemeteries not only serve as burial sites but also as a habitat for many animal and plant species, as the specific management of cemeteries creates conditions that hardly exist anywhere else. So-called stinzen plants are those plant species that show a connection to old garden cultures and need precisely these conditions. Many stinzen plants are early-flowering geophytes. We examined which factors influence the distribution and abundance (=cover values) of early-flowering geophytes at the largest cemetery in Austria, the Zentralfriedhof in Vienna, and tried to identify such stinzen populations. In spring 2020, we performed two vegetation surveys in 143 plots and recorded the occurrence and abundance (in %) of early-flowering geophytes. Then, we collected four variables for each plot: (1) cemetery type (architectural cemetery, park cemetery, and memorial), (2) care intensity, (3) type of use (path between graves, abandoned graves, free space between road and grave, and open meadow area with adjacent graves), and (4) distance to the next path. We recorded a total of nine different early-flowering geophyte species. All nine species were found on plots with very low care intensity. Only two species were found on paths between graves. Six species are listed as threatened on Vienna’s Red Data List. Two species, Eranthis hyemalis and Galanthus nivalis, are ornamental plants. Plots in the park cemetery have significantly lower average cover values of early-flowering geophytes than plots in the other two cemetery types. This can be explained by high maintenance measures and increased visitor pressure due to its location. Additionally, the data revealed that high care intensity seems to harm early-flowering geophytes. This study showed that cemeteries are refugia for protected species in urban areas and should, therefore, be considered in urban nature conservations.

Survival strategy of Watsonia fourcadei (Iridaceae); allocation of resources to sexual reproduction and vegetative survival of the parent plant

Geophytes are abundant in the Cape fynbos vegetation and many of the Cape geophytes, such as Watsonia species, flower mostly only in the first year after a fire. This study investigates the question if these plants have a resource allocation strategy which limits sexual reproduction to the post-fire environment and that they favor resource allocation to the storage organ for the survival of the parent plant at a cost to sexual reproduction. To test the hypothesis that the Cape geophyte Watsonia fourcadei represses sexual reproduction in favor of the survival of the parent plant, three levels of defoliation (20, 50 and 100%) were applied during a phenological stage when resources were least in the parent corms. Resource allocation to different plant parts was investigated when plants were in the seeding phase. Dry mass and nutrient (N, P. K, Ca, Mg and Ca) content were used as indicators of the resource allocation pattern. Dry mass and nutrient allocation patterns were similar, with significantly higher percentages of resources allocated to vegetative survival of the parent plant than to sexual reproductive organs (inflorescence and seeds) after complete defoliation, than after 20 and 50% defoliation. The W. fourcadei plants were able to accumulate adequate resources in the post-fire growth season to support sexual reproduction after up to 50% defoliation, albeit to a lesser extent than in control plants, but sexual reproduction was poorly supported after complete defoliation. Results indicate that W. fourcadei plants must be able to accumulate at least 3.5 g of dry mass in the new developing corm before resources are allocated to sexual reproductive plant parts. Replenishment of nutrient content after defoliation was not a limiting factor for resources allocation to sexual reproduction, except in the case of phosphate. W. fourcadei plants acted as a functional unit and resources allocation to sexual reproduction was controlled and depended on the availability of resources. None of the current resource allocation models are applicable to W. fourcadei and factors that could have selected for the apparent ‘K’ survival strategy in this and other Cape geophyte species are discussed.

Effects of heat treatment and chilling duration on camas growth and development

Great camas (Camassia leichtlinii (Baker) S. Watson [Asparagaceae]) and common camas (C. quamash (Pursh) Greene) are two of the most culturally and ecologically significant native geophyte species in the US Pacific Northwest. Like many geophytes, seasonal thermoperiodicity affects their growth and development. The daughter bulb of great camas grows and develops during the summer rest period. Increasing the duration of the summer rest period results in longer leaves in the subsequent growing season. Great camas, common camas, and meadow death camas (Toxicoscordion venenosum (S. Watson) Rydb. [Melanthiaceae]) require a period of chilling during their winter rest period to induce leaf emergence, and as the duration of chilling increases (1) the odds of leaf emergence increases, (2) the period between the cessation of chilling and leaf emergence decreases, and (3) leaf growth in the first week after leaf emergence increases. These results inform growers as to the proper storage methods for these species during their rest periods. Additionally, the chilling optimum, here defined as the amount of chilling at 4.6 °C that minimizes the duration of the winter rest period, is approximately 80 days for both great camas and common camas. However, this optimum was determined without considering a potential interaction with the heat treatment. Knowing the optimum duration of heat treatment and chilling may allow growers to manipulate native bulb species into emerging for multiple growing cycles in a single year, which could expedite their production.

Soil and plant outcomes of harvesting a Noongar staple geophyte in south-western Australia

Abstract Geophytes are a considerable component of Southwest Australian flora and thus, unsurprisingly, feature heavily in the diets and culture of Noongar First Nations people of this old, climatically buffered, infertile landscape-dominated global biodiversity hotspot. Of ~650 geophyte species recorded in south-western Australia, 90 are known traditional Noongar foods. Despite the significant role of geophytes in Noongar traditional lives, there is little published knowledge of the ecological effects of harvesting geophytes. We measured and observed soil and plant outcomes of tuber harvest for two Noongar staple species of Platysace Bunge to test whether it improved soil conditions for plant growth and/or aided tuber availability, as suggested for other Australian Aboriginal root crops. Harvesting of Platysace deflexa led to increases in some soil nutrient levels and, unexpectedly, to an increase in bulk density. Platysace deflexa stem abundance was restored to the pre-harvest level within 1 year post-harvest, whereas tuber weight and volume were less than pre-harvest levels after 2 years. A post-harvest increase in the proportion of small tubers in crops suggests that harvest has a renewing and homogenizing effect on tubers. Site-based differences in post-harvest P. deflexa and Platysace trachymenioides quantity of tubers were consistent with preferential harvest of some populations by present-day Noongar families and their ancestors.

Responses of Watsonia fourcadei and other geophytes to burning and slashing treatments in South Outeniqua Sandstone Fynbos

The often mass flowering of Watsonia and other geophyte species in the first year after a fire in the South African fynbos vegetation is well known, but it has rarely been quantified. Many fynbos geophytes also flower after the fynbos canopy was physically removed, but these flowering responses have also not been quantified. A study comparing the flowering response of geophytes after physical removal versus fire removal of the fynbos canopy was conducted to establish to what degree these species are fire dependant. It was also done to improve our understanding of fynbos geophyte ecology, especially towards establishing if the flowering response of these plants is due to fire related factors per se, or not.Vegetative growth, flowering response, seed set and seedling establishment of Watsonia fourcadei were recorded after two treatments, burning and physical removal of vegetation (slashing) in two veld ages (5- and 16 years). Responses of other co-occurring geophytic species to these treatments were also recorded. The number of vegetatively active W. fourcadei plants doubled and flowering percentage increased from 2.3% to 38.7% in the first year after the fire. In the second year after the fire the number of vegetatively active W. fourcadei plants was similar to those in the first year after the fire, but flowering percentage decreased to pre-fire levels. About 50% of W. fourcadei plants were dormant 5 years after the fire and > 90% were dormant in 16-year old fynbos. Flowering percentages of W. fourcadei in slashed 5-year old fynbos did not differ significantly from burned 16-year old fynbos. The flowering stimulus of W. fourcadei was thus not due to fire associated factors per se. Seed predation of W. fourcadei seed capsules decreased from 46.9% before the fire to 7.1% after the fire. Number of viable seed released increased from 15.8 seed mˉ² pre-fire to 1170.5 seed mˉ² post-fire and 233.1 seedlings mˉ² established after the fire. The 74-fold increase in seed release in the burned fynbos could not be ascribed to higher cross pollination success as about 40% of the flowers were autogamous. The number of vegetatively active geophytic species increased from 2.3 species mˉ² pre-fire to 7.9 species mˉ² post-fire in 16-year old burned fynbos and 4.0 species mˉ² in the slashed fynbos. Most (76%) of these geophytic species flowered after the fynbos was burned and 24% of the species flowered in the slashed fynbos. Only some of the geophytic species were thus dependent on fire to stimulate flowering. A repeated short cycle disturbance regime (ca. 5 years) of burning and/or slashing may result in a super-abundance of Watsonia plants that can displace smaller geophytic species. Previous hypotheses on proximate reasons for the Watsonia post-fire flowering that are rejected are: (i) greater visibility of the plants; (ii) heating of the soil and corms by fire and; (iii) increased availability of phosphorous and/or other minerals in the post-fire environment. Smoke as a factor to induce flowering in W. fourcadei growing under natural conditions is questioned.

Notes on the flowering stimulus of Watsonia fourcadei J.W. Mathews & L. Bolus

Watsonia fourcadei is one of the widespread geophyte species of the fire-prone fynbos vegetation of South Africa that flowers profusely in the first year after a fire. Although much has been researched on fire-stimulated seed germination, the effect of wildfire on flower elicitation in fynbos geophytes is less well researched. Hence, a study was undertaken to investigate the role of gibberellic acid in stimulating flowering of W. fourcadei. The hypothesis tested was that the plant hormone gibberellic acid (GA3) stimulates W. fourcadei plants to flower in situ. Unburned plants were injected with 2 ml of a solution of 50 µg GA3/ml distilled water in early spring and their flowering percentage was three times higher than those of control plants that were injected with 2 ml of water, and the untreated plants. The flowering percentage of plants treated with GA3 was equal to those of the plants found in the adjacent burned area. The endogenous biosynthesis of gibberellic acid in the post-fire environment seems to play an important role in stimulating W. fourcadei to flower and the ecological significance of this conclusion is briefly discussed.

Phloroglucinol Mediated Plant Regeneration of Ornithogalum dubium as the Sole "Hormone-Like Supplement" in Plant Tissue Culture Long-Term Experiments.

Tissue culture is an essential requirement in plant science to preserve genetic resources and to expand naturally occurring germplasm. A variety of naturally occurring and synthetic hormones are available to induce the processes of dedifferentiation and redifferentiation. Not all plant material is susceptible to tissue culture, and often complex media and hormone requirements are needed to achieve successful plant propagations. The availability of new hormones or chemicals acting as hormones are critical to the expansion of tissue culture potentials. Phloroglucinol has been shown to have certain hormone-like properties in a variety of studies. Ornithogalum dubium, an important geophyte species, was used to characterise the potential of phloroglucinol as the sole plant-like hormone in a tissue culture experiment. Tissue culture, plant regeneration, total phenolic and genetic variability were established by applying a variety of methods throughout long-term experiments. Phloroglucinol did induce callus formation and plant regeneration when used as the sole supplement in the media at a rate of 37%, thus demonstrating auxin/cytokines-like properties. Callus formation was of 3 types, friable and cellular, hard and compact, and a mixture of the two. The important finding was that direct somatogenesis did occur albeit more frequently on younger tissue, whereby rates of induction were up to 52%. It is concluded that phloroglucinol acts as a “hormone-like” molecule and can trigger direct embryogenesis without callus formation.