Organography and Plant Histology of Hydrocotyle umbellata (Araliaceae)

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Dear friends, followers and members of the Steem platform, in this delivery I will share organographic and histological elements, as well as the bioindicator potential shown by the aquatic macrophyte Hydrocotyle umbellata (ARALIACEAE) in contaminated ecosystems

Introduction

Aquatic plant specimens of the genus Hydrocotyle are macrophytes of cosmopolitan scope, generally used by naturalist medicine in Brazil and most Asian countries [1]. However, the scientific community's interest in studying these species focuses on their bio-indicator potential, in aquatic environments that show pollution, due to the presence of heavy metals.

Therefore, in this manuscript, the bio-indicating action of the aquatic macrophyte Hydrocotyle umbellata (Water Coin) will be described, in addition to providing botanical elements on the morphological, organographic and histological characterization of this species.

Biological classification

Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Apiales
Family: Araliaceae
Genus: Hydrocotyle
Species: umbellata

Common names

The aquatic macrophyte Hydrocotyle umbellata is known in the United States as Water coin, Colombia Redondita de agua, Cuba Ombligo de venus, México Sombrerito de agua, while in Venezuela it is called Lochita.

Origin and distribution

This aquatic macrophyte (Hydrocotyle umbellata), is native to North America, in relation to distribution is found in tropical regions and temperate zones, has expanded in most Caribbean countries, in South America there are reports of its presence in Brazil, Colombia, Chile, Ecuador, French Guiana, Peru and Venezuela.

Genus Hydrocotyle in Venezuela

The systematic study, carried out by [2], on the aquatic vascular plants of Venezuela, demonstrates that in the country, three species of aquatic macrophytes of the genus Hydrocotyle can be located, among these; Hydrocotyle humboldtii, Hydrocotyle umbellata and Hydrocotyle ranunculoides.

Bioindicator of contamination

Hydrocotyle umbellata proliferates in aquatic environments, which have high concentrations of pollutants [3], including heavy metals such as mercury (Hg), lead (Pb), cadmium (Cd), copper (Cu), iron (Fe), zinc (Zn) and chromium (Cr), so it can be used as a bioindicator species in polluted aquatic ecosystems.

Fig. 2 Hydrocotyle umbellata plants, growing in a contaminated aquatic ecosystem, by residual waste. Author: @lupafilotaxia.

Lochita extracts these toxic substances through its vegetative structures, becoming an ecologically and economically viable alternative, which can be used as biological material, in phytoremediation and wastewater treatment.

Botanical description

Way of life

According to the classification method referred to in [4], the life form of Hydrocotyle umbellata is located in the group of emerging rooted aquatic macrophytes, indicating that they are plants anchored to the substrate, with vegetative and reproductive structures protruding from the water sheet.

Fig. 3, 4-5 On the right Hydrocotyle umbellata seedlings. Upper left side, laminated foliar leaf, lower side adventitious roots. Author: @lupafilotaxia.

Root

Lochita, exhibits fibrous morphology root, with abundant adventitious roots in the knots.

Stem

Presents thick, crawling, rhizomatous and stoloniferous stems, which grow horizontally under the substrate.

Leaves

It has simple leaves, pecioladas, of pelted morphology (configuration of the circular leaf blade, with insertion of the petiole to the center of the limb), with slightly lobed edges, and nerves of palmatinervia morphology.

Fig. 6 -7 On the right, you can see a single sheet of Hydrocotyle umbellata, on the left, a type of petiolate insert is shown in the center. Author: @lupafilotaxia.

Inflorescence

Hydrocotyle umbellata, exhibits simple umbel inflorescence, arranged in umbrella form, with pedicels up to 25 cm long.

Flower

From 20 to 30 hermaphrodite or bisexual flowers, of tiny size, incomplete by the absence of sepals, petals of white color, free stamens and exhibits only one ovary.

Fruit

The fruit has a partially rounded morphology (suborbicular), dry aspect, and dehiscent when ripe.

Seeds

It has small seeds, strongly compressed, flat to convex aspect, with endosperm of woody consistency.

Fig. 8 Folded foil of Hydrocotyle umbellata, Hat-shaped. Author: @lupafilotaxia.

Reproduction

Sexual reproduction

Hydrocotyle umbellata reproduces sexually, in most South American countries has been reported pollination by insects, however, also participates in their reproduction, pollination of anemocoria type (wind).

Asexual reproduction

Lochita, as it is known in Venezuela, can be reproduced vegetatively, through growth and fragmentation of rhizomatous and stoloniferous stems, on the other hand, is aquatic macrophyte sometimes emits vegetative shoots, which come morphologically from the flowers.

Growth

Phenologically, the growth is usually very fast, in optimal climatic conditions and with high concentrations of mineral elements in aquatic ecosystems, being able to find 0.5 kg of foliar tissue per 1 m2, in a period of 7 days [2].

Life cycle

Lochita is a perennial aquatic macrophyte, with favorable growth in aquatic environments with low water levels.

Fig. 9 Proliferation of Hydrocotyle umbellata, in aquatic ecosystem, with low water level. Author: @lupafilotaxia.

Ecology

Flotation mechanism

Hydrocotyle umbellata, presents a less specialized flotation mechanism than the rest of the aquatic macrophytes such as Eichhornia crassipes, Limnocharis flava and Pistia stratiotes, this because histologically, their aeriferous chambers are underdeveloped.

Habitat and invasive condition

This aquatic macrophyte, habitat mainly on the shores of water bodies, shallow, moderately sloping, high pH, substrate with high organic matter content. In these conditions, Lochita has a high proliferation rate, which positions it as an invasive aquatic macrophyte, as far as the Southern Zone of Lake Maracaibo is concerned, it is usually found in drainage channels of urban communities.

Fig. 10 Hydrocotyle umbellata, growing in urban brocals, Santa Barbara de Zulia - Venezuela. Author: @lupafilotaxia.

Histology and organography

Microscopic study

The material of Hydrocotyle umbellata, used for the microscopic study, was collected from the drainage channel of one of the wetlands, from the Botanical Garden of UNESUR - Santa Bárbara de Zulia, Venezuela.

Fig. 11 Botanical dissection materials, to perform histological characterization of Hydrocotyle umbellata. Author: @lupafilotaxia.

Materials and reagents used

  • Plants of Hydrocotyle umbellata (Lochita)
  • Carrier sheets and coverslips
  • Botanical dissection team
  • Petri dishes
  • Optical microscope
  • Distilled water
  • Lugol
  • Safranin
  • Floroglucin

Characterization and histological identification

The samples of the leaves, petioles, rhizomes and adventitious roots were subjected to transverse and tangential histological cuts, the sections obtained were taken to the optical microscope in order to identify morphologically; the epidermis, stomas, parenchymal cells, mechanical and vascular tissues, observations were made at 10x.

Histological results

Epidermal characterization

The leaf of Hydrocotyle umbellata, presents epidermal cells in the adaxial and abaxial ends, of polygonal geometric morphology, thickened walls, thin and smooth cuticle, visible stomach apparatus in both faces and with stomas of paracític type.

Fig. 12 On the right side, a cross section of the leaf blade of Hydrocotyle umbellata is detailed, on the left side it is indicated, the location of the adaxial and abaxial epidermis of polygonal morphology, cortical parenchyma. Author: @lupafilotaxia.

Parenchymal characterization

The mesophilic Hydrocotyle umbellata leaf exhibits dorsiventral symmetry, circular parenchymal cells, appreciably polygonal, with cellular spaces, followed by irregular colenchymal cells, and with collateral vascular bundle.

Stoma characterization

Paracytic stomas were identified, arranged on both sides of the leaves, typical of anfistomatic stomas.

Fig. 13 On the right side, paracitic stomata are observed Hydrocotyle umbellata, on the left side, the shape of the anfistomatic stomatic apparatus is indicated. Author: @lupafilotaxia.

Aerenchymal characterization

In the cross section of the petiole of Hydrocotyle umbellata, polygonal epidermal cells were observed, followed by parenchymal cortical tissue of circular morphology, with visible intercellular spaces, and collateral vascular bundles, irregularly distributed around the pith.

Fig. 14 On the left side, the cross section of the Hydrocotyle umbellata petiole is detailed, on the right side, it is epidermis, parenchymal cells, arechimatic chambers and vascular bundle. Author: @lupafilotaxia.

Xylematic and phloematic characterization

The rhizomatic stem of Hydrocotyle umbellata, is constituted histologically by thin and smooth epidermal cells, cortical parenchyma of polygonal morphology, xylematic and phloematic cells, arranged in collateral vascular bundles, on the medullar circle, with protoxilemma towards the external side and metaxilemma towards the centre of the section.

Fig. 15 On the left side, the cross section of the Hydrocotyle umbellata rhizome is detailed, on the right side, the following tissues are identified in order; epidermis, cortical parenchyma, medulla, vascular bundle (Xylem and Phloem). Author: @lupafilotaxia.

SCIENTIFIC CONTRIBUTIONS OF THIS PUBLICATION


  • The manuscript served to present the organographic and histological characterization of Hydrocotyle umbellata, to describe its potential as a Bio-inidicator macrophyte in polluted aquatic ecosystems. On the other hand, the determination of the morphological elements of vegetative and reproductive organs, allow to enlarge the existing structural information, while the microscopic content is presented as, unpublished contribution of histological characterization of the specimens of H. umbellata, collected in the humidities of the South of the Lake – Venezuela.


BIBLIOGRAPHICAL REFERENCES CONSULTED AND CITED:


[1] Florentino I., Nascimento M., Galdino P., Brito A., Rocha F., Tonussi C., Lima T., Paula J., and Costa E. Evaluation of analgesic and anti-inflammatory activities of Hydrocotyle umbellata L., Araliaceae (acariçoba) in mice. An. Acad. Bras. Cienc. 2013; 85: 987-997.

[2] Velásquez J. Plantas acuáticas vasculares de Venezuela. Consejo de Desarrollo Científico y Humanístico, Universidad Central de Venezuela. 1994.

[3] Sopit P., Maleeya K., Prayad P., Varasya S., and Suchart U. Toxicity and Accumulation of Cadmium and Zinc in Hydrocotyle umbellate. ScienceAsia. 2006; 32: 323-328.

[4] Sculthorpe C. The Biology of Aquatic Vascular Plants. 610 S. London: Edward Arnold Ltd. 1967.

[5] Dushenkov V., Kumar P., Molt A., and Raskin I. Rhizofiltration: The use of plants to remove heavy metals from aqueous streams. Environ Sci Technol 29. 1995; 1239-45.

[6] Reddy K., and Tucker J. Growth and nutrient uptake of Pennywort (Hydrocotyle umbellata L.), as influenced by the nitrogen concentration of the water. J. Aquat. Plant Manage. 1985; 23:35-40.

[7] Solereder H. Systematic Anatomy of the Dicotyledons. The Clarendon Press, Oxford. Peer review under responsibility of Faculty of Pharmacy, Cairo University. 1985; 281-291.


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18 comments
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To listen to the audio version of this article click on the play image.

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Have a nice day, @lupafilotaxia.

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Thanks to the team of Talentclub, for having selected the article on: Organography and Plant Histology of Hydrocotyle umbellata (Araliaceae) among the posts that will receive additional TLNT tokens

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This post has been curated by Steemitas Club. Congratulations @lupafilotaxia and thank you for sharing this original work.

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Thank you friends of Steemitas Club, for again supporting the content that I have been socializing within the Steem platform. I will gladly promote this type of manuscript on your discord server.

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La lochita, otra macrófita fitorremediadora. Muy completa la entrada, no solo información para conocerla bajo distintos aspectos sino además, un aporte complementario con un estudio histológico. Éxitos @lupafilotaxia.

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Saludos amigo @capp, además del complemento histológico del escrito, un enfoque para la socialización de este tipo de contenido sobre Macrófitas acuáticas, es dar a conocer las principales características biológicas de estas especies vegetales, entre las cuales se destacan; su elevada reproducción vegetativa y sexual que las convierte en malas hierbas, al causar inconvenientes al cubrir y obstruir los cuerpos de agua, causando serios problemas en la actividad pesquera y el transporte lacustre en eco-regiones dónde existen problemas de eutrofización producto de actividades industriales, agrícolas y pecuarias.

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Hello:
A very interesting article. I actually looked this up elsewhere after reading your piece. I was curious about its medicinal properties. Found this: https://botanical.com/botanical/mgmh/h/hydcol46.html.

If it is a bio indicator (of pollution), doesn't that mean it also might pose a risk when used as a medicinal? Do people who harvest this for medicinal purposes understand that it absorbs pollutants so readily?

I wonder how the same issue might affect other plant-derived medicinals.

Thank you for a very informative article. Once again, you have wonderful pictures.

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Greetings @agmoore2, thank you for visiting the blog. The species you indicate Hydrocotyle asiatica (Centella asiatica), originally located in the genus Hydrocotyle, is not the same species described in this post (Hydrocotyle umbellata). In fact H. asiatica has multiple medicinal properties, which differentiate it from H. umbellata, characterized by its capacity to absorb pollutants in water ecosystems with eutrophication problems

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Thank you for clarifying that. Sorry....:)

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Thank you for this article. I am conducting a thesis related to this species but I can't identify whether I have H.vulgaris or H. umbellata. What would the difference between the two?

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Greetings friend @hh.
Thanks for your view.
Basically, H. umbellata leaves are larger, short internodes and petioles longer than H. vulgaris

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Thank you so much this helped me a lot!

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