Continuing with the dissemination of utilitarian botanical content, this time I will present an organographic, histological, taxonomic and ecological compendium of the aquatic macrophyte Hydrilla verticillata (Hydrocharitaceae).

Introduction

Hydrilla verticillata belongs to the category of submerged rooted aquatic macrophytes of invasive behavior, commonly known as elodea, hydrilla or water thyme, its high growth rate generates multiple ecological and socio-economic problems mainly in the United States of America and Australia.

The invasive behavior of Hydrilla verticillata is associated with the hydrophilic characteristic (pollen flotation) of the reproductive structures of its specimens, therefore, it can be inferred that this evolutionary advantage has allowed this aquatic macrophyte to adapt and ensure its pollination process in water conditions.

In this sense and taking into account the above information, the purpose of this manuscript is to socialize botanical content of organographic, histological, taxonomic and growth conditions, reproductive and ecological aspects exhibited by specimens of Hydrilla verticillata

Biological classification

Kingdom: Plantae

Division: Magnoliophyta

Class: Liliopsida

Family: Hydrocharitaceae

Gender: Hydrilla

Species: verticillata

Common names

Elodea is the most common descriptor or epithet used to identify specimens of Hydrilla verticillata, however, this submerged perennial aquatic macrophyte is also known as hydrilla or water thyme.

Ornamental potential and biological transport

The vegetative and reproductive structures of Hydrilla verticillata are widely used as ornamental material, either planted in moistened pots or to decorate ornamental aquariums both at home and in biological conservation institutions.

Fig. 2 Hydrilla verticillata is used as ornamental material and to decorate aquariums. Public domain image Author: Garg, 2009 / CC BY-SA 3.0

In addition to the ornamental potential exhibited by specimens of Hydrilla verticillata, it is important to mention that the extensive ecological biomass generated by the rhizomes of this aquatic macrophyte is often used as a biological vector to transport and disperse other invasive species to the shores of water bodies.

Origin and distribution

The specimens of Elodea come from the monotypic genus Hydrilla of uncertain origin, however, it is believed that it may have originated in meso-thermal waters of the Asian continent, it exhibits pantropical distribution hence it has a wide geographical occurrence, and can be found in naturalized areas of a large number of countries in Europe, Africa, Australia, North America and South America.

Botanical description

Way of life

The aquatic macrophyte Hydrilla verticillata is of annual biotype, herbaceous consistency, perennial growth, and submerged behavior supported by a rooting system with rhizomatous development parallel to the ground.

Fig. 3 Hydrilla verticillata is of annual biotype and herbaceous consistency. Public domain image Author: Krzysztof, 2016 / CC BY-SA 4.0

Root

Hydrilla verticillata has rhizomatic shoot roots and adventitious origin.

Stem

It exhibits herbaceous, long, flexible, filiform and branched stems.

Leaves

Leaf blades are filiform/elliptic, sessile, with serrated/serrated edges, acute apex and phyllotaxy in the form of whorls.

Fig. 4 The leaves of Hydrilla verticillata are filiform/elliptic in appearance, sessile, with serrated/serrated edges. Public domain image Author: Darkmax, 2008 / CC BY-SA 3.0

Flower

Specimens of Hydrilla verticillata are characterized by unisexual flowers, with female reproductive units with long peduncles and male flowers without peduncles.

Reproduction

Sexual reproduction

Within the group of submerged rooted aquatic macrophytes Hydrilla verticillata has the greatest reproductive advantage, because it has the ability to reproduce sexually through two biotypes, namely through a dioecious system of male and female flowers in different specimens, and also through the monoecious system with male and female flowers in the same specimen.

Asexual reproduction

In addition to the successful sexual reproductive system exhibited by Hydrilla verticillata, it also has the biological potential to reproduce by fragmentation and by vegetative dispersal via stolons, rhizomes, axillary tubers, and subway tubers.

Growth

Hydrilla verticillata has a high growth rate due to the ability of its specimens to adapt to water bodies with different chemical composition, wide pH range, varied depth and low light intensity, elements that place it among the most invasive aquatic macrophytes.

Ecology

The high growth rate exhibited by specimens of Hydrilla verticillata enables them to compete with native aquatic macrophytes of strongly moving water habitats of both tropical and temperate ecosystems, a behavior that allows them to colonize water bodies to the point of causing serious socioeconomic and ecological problems.

Fig. 5 Hydrilla verticillata competes with aquatic macrophytes native to strongly moving water habitats of both tropical and temperate ecosystems. Public domain image Author: Yercaud, 2016 / CC BY-SA 4.0

Anatomy and Histology

The leaf lamina of Hydrilla verticillata is characterized by having only two adjacent epidermal layers, whereas the leaf mesophyll exhibits a single vein constituted by four vascular cell layers in concentric order leaving numerous intercellular spaces.

SCIENTIFIC CONTRIBUTIONS OF THIS PUBLICATION

The socialized content aimed to share with the users of the academic community that coexist in the #Hive platform, descriptive information of botanical character mainly material on the ecological relevance that exhibits the aquatic macrophyte Hydrilla verticillata to adapt to water bodies in both tropical and temperate ecoregions, biological response associated with the hydrophilic characteristic presented by these specimens of rooted and submerged behavior.

BIBLIOGRAPHICAL REFERENCES CONSULTED AND CITED:

[1] Cook C A revision of the genus Hydrilla (Hydrocharitaceae). 1982. Article: Online access

[2] Balciunas J., Grodowitz M., Cofrancesco A., and Shearer J Hydrilla. 2002. Article: Online access

[3] Efremov A., Yana B., Mesterhazy A., Toma C Features of Distribution of Hydrilla verticillata (L. fil.) Royle (Hydrocharitaceae) in North Eurasia. Journal of Coastal Research. 2017; 34: 3. Article: Online access

[4] Pendland J Ultrastructural characteristics of Hydrilla leaf tissue. Tissue and Cell. 1999; 11; 1: 79 – 88. Article: Online access

[5] Dan Yu J., and Xu X The phylogeographic structure of Hydrilla verticillata (Hydrocharitaceae) in China and its implications for the biogeographic history of this worldwide-distributed submerged macrophyte. BMC Evolutionary Biology volume. 2015; 15: 95. Article: Online access

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OBSERVATION

✔ The cover image was designed by the author: @lupafilotaxia, incorporating the public domain background image, Author: Mokkie, 2013, 2014 / CC BY-SA 3.0

My Actifit Report Card: July 16 2019