Category Archives: Botany

Friday Fellow: Blue Jacaranda

by Piter Kehoma Boll

Let’s keep the trend of last week and present again a South American species, but today’s fellow has moved way beyond its original range.

Scientifically known as Jacaranda mimosifolia, the common names of this species are blue jacaranda, fern tree or simply jacaranda. Its native range includes a considerably small area between Argentina and Bolivia, but it is grown as an ornamental tree throughout the whole world.

Flowers of a specimen in its native range in Argentina. Photo by Martin Arregui.*

An iconic tree, the blue jacaranda reaches up to 20 m in height. Its bark is smooth at first but later becomes scaly and rough as it typical of trees of the family Bignoniaceae, to which it belongs. The leaves are large, up to 45 cm long, and are bipinnately compound, i.e., the compound leaf itself consists of compound leaflets, which is likely the reason why it is sometimes called fern tree.

A blue jacaranda leaf. Photo by Wikimedia user Crusier.**

The flowers are, however, the most iconic feature of this tree, appearing in spring and early summer. They are tubular, reach about 5 cm in length, have a pale purple-indigo color and are grouped in large panicles. The fruits are dry woody pods with a somewhat oval shape and are often gathered for decoration purposes, including the decoration of Christmas trees or as body ornaments, such as the confection of earrings.

The dry woody pods of the blue Jacaranda. Photo by Wikipedia user Babbage.**

The wood of the blue jacaranda has a light color and is considerably soft, being often used for the creation of sculptures and bowls, especially when still green.

Wood of the blue Jacaranda. Photo by Wikimedia user SybillKaesedick.***

The blue jacaranda became an important cultural element in many regions of the world. It is often featured in songs, especially in Argentina and Brazil. In South Africa, the city of Pretoria is also known as the Jacaranda City due to the large number of blue jacarandas that turn the city blue in Spring. In Australia, the blue jacaranda became associated with the final exams of students in the University of Queensland, which is known for its jacarandas. The trees flower during the time the students are running to complete their assignments and study for their final exams, which give rise to the expression “purple panic”.

A blue jacaranda in Campinas, Brazil. Photo by Enio Prado.**

Despite its widespread occurrence as an ornamental plant, the blue jacaranda is considered vulnerable in its native habitat by the IUCN’s Red List. In other areas, such as South Africa and Australia, for example, the tree is sometimes an invasive species, outcompeting native trees by blocking their growth.

Blue jacaranda trees in Pretoria, South Africa. Photo by Paul Saad.***

Due to such negative impacts, planting new jacarandas in Pretoria is now forbidden. The idea of removing the adults trees, which was the original plan, was discarded due to their popularity with locals. Nevertheless, in some decades or centuries (provided that humanity will survive that much as a civilization), the Jacaranda City will eventually lose all its Jacarandas.

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References:

Prado D (1998) Jacaranda mimosifolia. The IUCN Red List of Threatened Species 1998: e.T32027A9675619. https://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T32027A9675619.en Access on 17 September 2020.

Wikipedia. Jacaranda mimosifolia. Available at < https://en.wikipedia.org/wiki/Jacaranda_mimosifolia >. Access on 17 September 2020.

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*Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

**Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

***Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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Friday Fellow: Common Pellia

by Piter Kehoma Boll

Liveworts often live in moist and shady spaces and, even if we know how to identify them as liverworts, they often look all the same. However, if we pay attention to the details, differences can often be perceived.

Pellia epiphylla, commonly known as the common pellia, is a liverwort that loves very humid places, so it often grows very close to rivers and other watercourses in North America, Europe, North Africa and some nearby areas in Asia. Its thalli are smooth and slightly fleshy, about 1 cm wide and can reach several cm in length. They like ro remain in a horizontal position, so they grow very attached to the horizontal subtrates but tend to grow away in vertical ones, acquiring a more ruffled aspect. Although usually completely green, the thalli can have a purplish or reddish tinge along the middle, especially when they grow too far from water, which can help identify this species. Otherwise it is very featureless compare to many other liverworts.

File:Pellia epiphylla7 ies.jpg
The typical aspect of the common pellia. Some thalli can be seen with a purplish tinge in the middle. Photo by Frank Vincentz.**

As with all liverworts, the thallus of the common pellia is the gametophyte, i.e., the haploid generation (with only one chromosome of each type per nucleus) and that generates the gametes. Although in many liverworts the gametophytes are either male or female, they are monoicous (i.e, hermaphrodites) in the common pelia. The male sex organs (antheridia) occur along the middle, appearing as very small light and shiny dots, while the female ones (archegonia) occur close to the tip and remain covered. Fertilization, as usually, occurs when the plant becomes wet. The antheridia absorb water to the point that they burst, releasing the sperm cells (antherozoids) that swim to the archegonia, where fertilization occurs.

Young sporophytes growing from inside the archaegonia. Photo by Hermann Schachner.

The resulting zygote gives rise to the sporophyte, a diploid generation (with two chromosomes of each type per nucleus) and it grows from inside the archegonia in the form of a very long and slender whitish stalk with a dark capsule at the tip. When the capsule is mature, it bursts and releases the spores, which will germinate and originate new gametophytes. The group of sporophytes growing from the gametophyte give the set a peculiar “hairy” aspect, which also helps recognize this species.

When the sporophytes grow, they give the family a hairy look. Photo by Roger Griffith.

Being a common species across its range, the common pellia has been studied to understand physiological and reproductive characteristics of liverworts, as well as some ecological aspects. For example, it is known that, while the gametophyte absorbs water mostly through the under surface, the antheridia absorb it from the upper surface, and the lower midrib of the plant compared to the border is essential to retain water for this. While the sporophyte of many liverworts is completely dependent on its mother, the gametophyte, to receive water, that of the common pellia is much more indepenent, absorbing most of it from the environment.

Although fairly featureless, the common pellia still has its charm.

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References:

Clee A (1939) The Morphology and Anatomy of Pellia epiphylla considered in Relation to the Mechanism of Absorption and Conduction of Water. Annals of Botany 3(1): 105–111. https://doi.org/10.1093/oxfordjournals.aob.a085045

Greenwoo HE (1911) Some Stages in the Development of Pellia epiphylla. The Bryologist 14(4): 59-70. https://doi.org/10.2307/3238074

Wikipedia. Pellia epiphylla. Available at <https://en.wikipedia.org/wiki/Pellia_epiphylla >. Access on 27 August 2020.

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Friday Fellow: Dragon Tree

by Piter Kehoma Boll

When the seventh generation of pokémon was released, it introduced regional forms of previous pokémon, including an Alolan form of Exeggutor which was changed from the grass/psychic type of the traditional Exeggutor to a grass/dragon type. This led many people to become familiar with the genus Dracaena, a genus that is well-known among botanists and gardeners and includes many ornamental plants.

Alolan Exeggutor, a grass/dragon pokémon.

The name Dracaena comes from the greek word meaning dragoness, i.e., a female dragon and is given based on the type-species of the genus, Dracaena draco, or the dragon tree, which is today’s fellow.

Dragon tree in Tenerife, Canary Islands. Photo by Wikimedia user Losrealejos.es*

The genus Dracaena is closely related to the genus Asparagus and the dragon tree was intially named Asparagus draco by Linnaeus and later renamed Dracaena draco by himself based on a genus name created by the Italian naturalist Domenico Agostino Vandelli. This species is native from the African islands in the Atlantic (Canary Islands, Cape Verde and Madeira).

Closeup of a flower. Photo by Wikimedia user Philmarin.**

The dragon tree starts its life as a small unbranched stem like most ordinary species of Dracaena we see in gardens. Its growth is very slow and only after growing vertically for 10 to 15 years it will produce flowers for the first time. The flowers are white and lily-like and appear in a spike, later turning into reddish berries. After this first reprouctive cycle, the stem branches for the first time from a crown of terminal buds and then grows again for 10 to 15 years before branching again. Being a monocot, the dragon tree lacks growth rings but its age can be estimated by the number of branching points from the ground to the crown.

File:Starr-120403-4177-Dracaena draco-fruit and leaves-Kula-Maui (24842899630).jpg
The fruits. Photo by Forest & Kim Starr.***

The association of this plant with dragons comes from ancient times. Not only Dracaena draco, but some other species of Dracaena as well, produce a red resin that is secreted when the leaves or the trunk are cut. A similar red resin is found in many other plants, including palm trees and crotons, and they were all collectively known as “dragon’s blood” and used for several purposes, such as dye or medicine. The ancient Romans collected dragon’s blood from the Island of Socotra, where a closely-related species, Dracaena cinnabari, the dragon’s blood tree, is found.

Plucked dead leaves showing the red color of the dragon’s blood. Photo by Wikimedia user Sharktopus.*

The dragon tree is the official tree of Tenerife, where the largest and possibly oldest specimen is also found, the so-called “Drago Milenario”. This specimen is about 21 m tall but, despite its name (the thousand-year-old dragon), it is not actually that old and its age is most likely about 300 years or so.

The Drago milenario in Tenerife, the largest dragon tree in the world. Photo by Andrey Tenerife.**

Despite being a relatively popular species that is grown as an ornamental plant, the dragon tree is classified as vulnerable in the IUCN’s red list. It’s wild populations are close to extinction and one reason for this is likely because some of its original seed dispersers went extinct. Only two bird species have been recently recognized as effective dispersers. Due to the dragon’s tree relatively large fruit, most bird species do not eat the whole fruit and only bite off pieces of the pulp, so that seeds are not carried to new locations.

File:Dracaena draco 1.jpg
Ripe fruits. Photo by Wikimedia user Nadiatalent.*

The Guanches, the aboriginal people of the Canary Islands, used to worship a large dragon tree in Tenerife. Alexander von Humboldt apparently saw this tree when visiting the island and it was later destroyed by a storm that hit Tenerife in 1868. The Guanches were wiped out by the Spanish invaders and now their sacred tree is facing the same fate.

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References:

Bañares A et al. (1998) Dracaena dracoThe IUCN Red List of Threatened Species 1998: e.T30394A9535771. https://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T30394A9535771.en. Access on 13 August 2020.

González-Castro A, Pérez-Pérez D, Romero J, Nogales M (2019) Unraveling the Seed Dispersal System of an Insular “Ghost” Dragon Tree (Dracaena draco) in the Wild. Frontiers in Ecology and Evolution 7:39. https://doi.org/10.3389/fevo.2019.00039

Wikipedia. Dracaena draco. Available at < https://en.wikipedia.org/wiki/Dracaena_draco >. Access on 13 August 2020.

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Friday Fellow: Busy Lizzie

by Piter Kehoma Boll

You probably know today’s fellow. You may have this plant in your garden or have seen it in someone else’s garden, in parks or, if you live in tropical and subtropical areas, everywhere along roads or inside the forest. Scientifically known as Impatiens walleriana, it is commonly called busy Lizzie, sultana, impatiens or balsam, although impatiens and balsam can be used for other species of the genus Impatiens.

Busy Lizzie in Vietnam. Credits to Wikimedia user Prenn.**

This lovely plant has tender and succulent stem with a light green to dark red color that becomes semiwoody at the base. The leaves are tender, ovate, smooth and have a serrated border. The base of the leaves have small extrafloral nectaries. The flowers have 5 petals and 5 sepals and are bilaterally symmetric, with the lower sepal forming a long spur containing nectar. The fruits develops into a small capsule that explodes as a strategy to spread the seeds.

Extrafloral nectaries dripping. Photo by Wikimedia user Mariluna.**

The busy Lizzie is native from eastern Africa and is cultivated worlwide as an ornamental plant, with several different cultivars. The flowers can be white, pink, salmon, red, magenta, purple and many other varieties, sometimes even with more than one color. Interesting, though, a study revealed that white is the favorite color for butterflies that visit the plant, while red is the least favorite color. In fact, although different butterfly species show slightly different preferences for color, no species seems to like visiting red flowers.

A specimen growing in South Africa. Photo by Stuart Billingham.*

After being transported to other continents, the busy Lizzie become naturalized in many regions, especially tropical and subtropical areas in the Americas and southeast Asia. The impact of its spread throughout these areas is not clear as far as I know.

Several varieties being cultivated in Bangalore, India. Photo by Ramesh Ng.**

One interesting fact is that mosquitoes seem to love feeding on its extrafloral nectaries, and studies have shown that they are the preferred nectar source for mosquitoes of the genus Aedes. Thus, the busy Lizzie is know being studied as a potential way to control the populations of these disease-carrying insects by the development of genetically modified varieties with inseticidal nectar.

Other studies have shown that the busy Lizzie is a cadmium accumulator, i.e., it can remove large amounts of cadmium from the soil and has the potential do be used as a tool for decontamination. Busy Lizzie is very busy, indeed.

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References:

Lai H-Y (2015) Subcellular distribution and chemical forms of cadmium in Impatiens walleriana in relation to its phytoextraction potential. Chemosphere 138:370–376. https://doi.org/10.1016/j.chemosphere.2015.06.047

Lim TK (2013). Impatiens walleriana. Edible Medicinal and Non-Medicinal Plants: 548–550. https://doi.org/10.1007/978-94-007-7395-0_34

Mandle M, Warren DL, Hoffmann MH, Petersen AT, Schmitt J, von Wettberg EJ (2010) Conclusions about Niche Expansion in Introduced Impatiens walleriana Populations Depend on Method of Analysis. PLoS ONE 5(12): e15297. https://doi.org/10.1371/journal.pone.0015297

Morris AB (2005) Functional differences among color morphs of Impatiens walleriana (Balsaminaceae).

Pruett G, Hawes J, Varnado W, Deerman H, Goddard J, Burkett-Cadena N, Kearney C (2020) The readily transformable Impatiens walleriana efficiently attracts nectar feeding with Aedes and Culex mosquitoes in simulated outdoor garden settings in Mississippi and Florida. Acta Tropica. https://doi.org/10.1016/j.actatropica.2020.105624

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Friday Fellow: Red Bogmoss

by Piter Kehoma Boll

Among the many different ecosystems found on Earth, bogs are particularly interesting. These peculiar wetlands are basically a large amount of water-soaked plant matter, either dead or alive. Usually very acidic, bogs have very low decomposition rates, so plant matter tends to accumulate more and more, sometimes reaching several meters in depth.

The main organisms responsible for the formation of bogs are mosses of the genus Sphagnum, commonly known as bogmosses or peatmosses (peat being the plant material that forms the bogs). Found all around the world, bogmosses have the ability to absorb huge amounts of water, just like a sponge, and in dry conditions they can release this water into the surrounding areas, helping them stay humid.

Red bogmoss in Canada. Credits to iNaturalist user maddieology.*

One bogmoss species, the red bogmoss, Sphagnum capillifolium, is found in the northern half of North America and Europe, being an important and genetically diverse species. In fact, it is likely that the red bogmoss is actually a complex of many very similar species. Its scientific name, capillifolium, meaning “hair-leaf”, refers to the peculiar shape of the plant, which grows in straight and densely packed branches that bent outwards at the top, resembling tresses.

Greener specimens in the USA. Photo by Joe Walewski.*

Although most bogmoss species are green like any regular plant, the red bogmoss and closely related species can have a reddish color. However, this color is not caused by pigments in their plastids but by a pigment, sphagnorubin, found in their cell walls. The presence or not of sphagnorubin seems to be determined by certain combinations of temperature, light and hormones. The exact function of sphagnorubin is unknown, but there have been suggestions that it may help protect the plant from herbivory. It i also possible that this reddish color works as a sunscreen, protecting the plant’s chloroplasts from intense radiation since sphagnorubin absorbs UV and blue light.

A very red and water-soaked mass in Scotland. Credits to Andrew Melton.*

Bogmosses in general are not attractive to herbivores because they contain high amounts of phenolic compounds, such as tannins, which gave them an adstringent and bitter taste. These phenolic compounds are also the main reason why peat takes such a long time to decompose. As a result, bogs function as huge carbon reservoirs, and about 10 to 15% of all carbon stock on the planet is in the form of Sphagnum. In fact, the amount of carbon fixed by all other photosynthetic lifeforms on Earth every year is lower than the amount held in bogs.

Some slightly red ones in England. Photo by Jeremy Barker*.

Sphagnum is, thus, an essential genus to keep the levels of carbon dioxide in the atmosphere low and the red bogmoss is even more important because it seems to be a very tolerant species that can survive in both shaded and sunny environments, as well as conditions with low and high levels of nitrogen and may, therefore, resist human interference better than other bogmosses.

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References:

Bonnett SAF, Ostle N, Freeman C (2009) Short-term effect of deep shade and enhanced nitrogen supply on Sphagnum capillifolium morphophysiology. Plant Ecology 207: 347–358. https://doi.org/10.1007/s11258-009-9678-0

Gerdol R, Bonora A, Marchesini R, Gualandri R, Pancaldi S (1998) Growth Response of Sphagnum capillifolium to Nighttime Temperature and Nutrient Level: Mechanisms and Implications for Global Change. Arctic and Alpine Research 30(4): 288–395. https://doi.org/10.1080/00040851.1998.12002914

Verhoeven JTA, Liefveld WM (1997) The ecological significance of organochemical compounds in Sphagnum. Acta botanica neerlandica 46(2): 117–130. http://natuurtijdschriften.nl/record/541086

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Friday Fellow: Tulip Tree

by Piter Kehoma Boll

When people reach a new locality and find new species, they have to think of a way to name them, which can happen by borrowing a name from a local language or make up a new name from one’s own language. When the first Europeans reached North America, they discovered a beautiful tree growing in what is now eastern United States. The Miami people called it oonseentia, but we all know how Europeans treated native Americans back then. So, instead of borrowing this word, they made up a new and completely misleading name: tulip tree.

Cultivated tulip tree in Belgium. Photo by Jean-Pol Grandmont,**

Linnaeus gave this tree its currently accepted binomial name: Liriodendron tulipifera, literally meaning “lily tree that carries tulips”. However, this species has nothing to do with lilies and tulips, being actually closely related to magnolias.

Reaching up to 50 m in height, and rarely becoming even taller, the tulip tree has a brown and furrowed bark and smooth and lustrous branches. The leaves have four large lobes that, if you make a lot of effort, may look a little bit like a violin, which makes it have an additional common name: fiddletree.

Typical “violin”-shaped leaf from a tree in Virginia, USA. Credits to Wikimedia user PumpkinSky.*

The flowers of the tulip tree appear in summer and very superficially resemble a tulip, although their structure is quite different. They have three green sepals and six petals that are arranged in a spiral that continues inward to form the stamens and then the pistils, which form a central cone. This arrangement is considered primitive within angiosperms and kind of look as something between a gymnosperm cone and a true angiosperm flower.

Flowers on a tree in New Jersey, USA. Photo by Wikimedia user Famartin.*

The mature seeds, called samaras, are dispersed by wind. They develop in autumn and are stored in a type of cone-like fruit. As a typical temperate species, the tulip tree is deciuous, shedding its leaves in winter.

Frosted fruits in winter in Virginia, USA. Photo by Jörg Peter.

The tulip tree is considered a species that dominates the first century of a forest since its establishment. It is a shade-intolerant species, so when other trees start to grow among them and block much of the sunlight, they tend to perish.

Due to its beauty, the tulip tree has become an ornamental plant and several cultivars have been developed. Its wood is also used for construction, and Native Americans used to build canoes from its trunks. Due to its wood, the tulip tree has also received the common name “yellow poplar” although it is not closely related to the true poplars, such as the black and white poplar. In fact, their wood is not that similar, with the tulip tree or “yellow poplar” wood being of much higher quality. In other words, the name “yellow poplar” is as misleading as the name “tulip tree”.

Big and old tulip trees in the Joyce Kilmer Memorial Forest, North Carolina, USA. Photo by Wikimedia user Notneb82 .**

The orange part of the petals contain nectar that, when collected by bees, creates a special and strong honey that is usually considered unsuitable for table honey but highly regarded by bakers.

Native Americans and early European settlers used the tulip tree to treat malaria, and modern studies have confirmed that some of its constituents show antiplasmodial activity, as well as antioxidant, antimicrobial and cytotoxic properties, having the potential to help the development of new antibiotics and anticancer drugs.

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References:

Quassinti L, Maggi F, Ortolani F, Lupidi G, Petrelli D, Vitali LA, Miano A, Bramucci M (2019) Exploring new applications of tulip tree (Liriodendron tulipifera L.): leaf essential oil as apoptotic agent for human glioblastoma. Environmental Science and Pollution Research 26:30485–30497. https://doi.org/10.1007/s11356-019-06217-4

Wikipedia. Liriodendron tulipifera. Available at: <https://en.wikipedia.org/wiki/Liriodendron_tulipifera>. Access on June 18, 2020.

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Fighting Aedes mosquitoes with carnivorous plants

by Piter Kehoma Boll

Two mosquitoes of the genus Aedes, Aedes aegypti and Aedes albopictus, are invasive species in tropical and subtropical regions worldwide. While A. aegypti is native from Africa, A. albopictus is originally from southeast Asia, but both species have been spread by humans and continue to increase their range.

Both species are known as vectors of several diseases that affect humans, especially those caused by Flavoviruses, which include the Yellow fever, Dengue fever and Zika fever. Chikungunya, caused by a species of Alphavirus is also transmitted to humans by them. Moreover, they can also transmit some nematodes, such as the heartworm that infects the heart of dogs and other carnivores.

Aedes aegypti biting a human and having a delicious bloody meal. Photo by James Gathany.

Because A. aegypti and A. albopictus pose such a huge threat to public health, getting rid of them is top priority. Here in Brazil, there is a massive national campaign to reduce the ability of Aedes to reproduce by avoiding containers with still water in the open, such as flower vases, buckets, uncovered barrels, discarded tires and virtually everything that can retain water long enough for the larvae to develop. I have to say, though, that this all seems to be useless. The mosquitoes continue to spread and the cases of dengue fever continue to grow. The fact is that the mosquitoes will find a place to lay their eggs. If they don’t find it in your backyard, they will find it in the forest or any vacant lot.

Instead of forcing them to lay their eggs where we cannot see, we should stimulate them to lay their eggs around us and then kill the larvae. Several aquatic predators have been tested as potential allies, including larvivorous fish, dragonfly nymphs, copepods, planarians and even other mosquitoes whoses larvae eat the larvae of Aedes! The use of these predators showed mixed results. Larvivorous fish are difficult to maintain in water tanks at home and dragonfly nymphs are too generalist as predators.

Now a new predator has been suggested: a plant! Yes, a carnivorous plant of the genus Utricularia, which includes species known as bladderworts. These aquatic plants have little bladder-like structures that function as traps to capture small animals. The bladder is hollow and has an internal negative pressure in relation to the environment surrounding it. This negative pressure is created by water being constanly pumped out of the bladder through its walls via active transport. The bladder’s opening is covered by a small lid that avoids water to fill it again when the trap is set. Surrounding the lid, there is a group of bristle-like protuberances. When an animal is moving through the water and moves one of those bristles, they slightly deform the lid, breaking the seal and allowing water to enter the bladder. The negative pressure then sucks water quickly into the bladder, dragging the small animal with it. Then it is only a matter of time for the poor animal to be digested.

Watch the plant in action.

A group of researchers at the University of Rhode Island, USA, tested whether Utricularia macrorhiza, the common North American bladderworth, could be an effective predator of mosquito larvae. By adding U. macrorhiza to containers with larvae of A. aegypti and A. albopictus, they were able to kill 95 to 100% of the larvae in only five days. That’s an amazing result, don’t you think?

Bladderwort with several Aedes larvae (marked with asterisks) in its traps. Credits to Couret et al. (2020).*

Since bladderworts are much easier to raise in tanks and other containers in your backyard than animal predators such as fish and dragonflies, they are a promising new alternative to control the populations of this disease-carrying insects.

So, are you eager to raise some aquatic carnivorous plants to help fight these heinous mosquitoes?

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References:

Couret J, Notarangelo M, Veera S, LeClaire-Conway N, Ginsberg HS, LeBrun RL (2020) Biological control of Aedes mosquito larvae with carnivorous aquatic plant, Utricularia macrorhizaParasites Vectors 13, 208. https://doi.org/10.1186/s13071-020-04084-4

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Friday Fellow: Red Globe Thistle

by Piter Kehoma Boll

The family Asteraceae (or Compositae), sometimes called “the daisy family”, is the largest family of plants, with more than 30 thousand currently accepted species. This family is characterized by a typical inflorescence called capitulum (or head in English), which is formed by several small flowers arranged in a compact form so that the whole structure resembles a single flower. One of its subfamilies, Carduoideae, include species known as thistles and, among them, one genus, Echinops is quite unusual among the whole family.

The heads of Echinops, different from most Asteraceae, contains a single flower, and these single-flowered heads are arranged in secondary inflorescences that form a globose structure, Thus, species of Echinops are named ‘globe thistles’. Most species of globe thistle have blue or white flowers but one species, Echinops amplexicaulis, has a dark red color. Although not having a common name in English as far as I know, I think that ‘red globe thistle’ is an excellent name.

Red globe thistle in Ethiopia. Photo by Alberto Vascon, extracted from centralafricanplants.senckenberg.de

Found in dry grasslands and dry forests in Central Africa, the red globe thistle reaches a height of about 1 to 1.5 m and has a vertical, usually unbranched stem with hardened leafs whose margin is dentate and the lobes have a terminal spine, as typical of thistles.

Specimen in the Democratic Republic of the Congo. Photo by Mathias D’haen.*

The roots of the red globe thistle are traditionally used in Uganda and Ethiopia to treat a series of conditions, including AIDS, trypanosomiasis, ulcerative lymphagitis, hydrocele, tuberculosis and stomachache. Laboratory studies have identified anti-tuberculosis activity of the root extract in vitro against several strains of Mycobacterium, including strains resistant to the currently common drugs used to treat the infection.

Apparently there is no study addressing the other alleged effects of the plant. There are also no studies on the ecology or life cycle of this species. In other words, that’s all I can tell about this lovely and peculiar globe thistle.

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References:

Bitew H, Hymete A (2019) The Genus Echinops: Phytochemistry and Biological Activities: A Review. Frontiers in Pharmacology 10: 1234. https://doi.org/10.3389/fphar.2019.01234

Kevin K, Kateregga J, Carolyn N, Derrick S, Lubega A (2018) In Vitro Anti-tuberculosis Activity of Total Crude Extract of Echinops amplexicaulis against Multi-drug Resistant Mycobacterium tuberculosis. Journal of Health Science 6: 296–303. https://doi.org/10.17265/2328-7136/2018.04.008

Tadesse M (1997) A revision of the genus Echinops (Compositae-Carduae) in Tropical Africa. Kew Bulletin 52(4):879–901. https://doi.org/10.2307/4117817

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Friday Fellow: African Feather Grass

by Piter Kehoma Boll

Grasses make up one of the most successful families of flowering plants and are the main characters in grasslands, which can cover huge areas of Earth’s surface. Not all species cover large areas, though, at least not in their native habitats. One example is Pennisetum macrourum, the so-called African feather grass.

Native from South Africa and nearby countries, the African feather grass is a perennial species that grows in soils that experience periodic flood. Thus, it usually grows around larger water bodies or in areas that form temporary ponds during the rainy season.

A patch of African feather grass in the Kruger National Park in South Africa with a southern greater kudu (Tragelaphus strepsiceros strepsiceros) in the background. Photo by Johnny Wilson.*

Growing up to 2 m in height, the African feather grass grows in dense patches and does not spread evenly across the substrate. It produces the typical inflorescence of the genus Pennisetum, a narrow and dense panicle with spikelets interspersed with bristles, giving it a fluffy aspect. The fresh panicle is light green to white but turns light brown when ripe.

Closeup of a panicle. Photo by Douglas Euston-Brown.*

While most grasses die during the dry season, the African feather grass persists throughout the year, being an important food source for wild grazing animals and is also given as food for domesticated cattle. It is not a very tasteful and nutritious grass, though, and most animals avoid eating it when other grasses are available.

A patch in Stellenbosch, South Africa. Photo by Dave Richardson.*

Despite its importance for native species in Africa, the African feather grass has gained the status of a vilain elsewhere. The species was introduced in New Zealand and Australia and became an noxious weed. Spreading quickly throughout the environment, the African feather grass outcompetes native grasses and is not regarded as a high quality food for grazing animals there either. Nevertheless, I was unable to find any recent work addressing this situation, including the current status of this grass in the aforementioned countries and ways to control its spread.

Panicles covered with spider web and dew in New Zealand. Photo by iNaturalist user ben_banks.*

It seems that is still a lot to be studied about this African grass in both its native habitats and places where it was introduced.

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References:

Brewer J, Loveless AR (1977) Ergot of Pennisetum macrourum in South Africa. Kirkia 10(2):589–600.

Harradine AR (1980) The biology of African feather grass (Pennisetum macrourum Trin.) in Tasmania, I. Seedling establishment. Weed Research 20(3):165–168. DOI: 10.1111/j.1365-3180.1980.tb00063.x

Shem M, Mtengeti EJ, Luaga M, Ichinohe T, Fujihara T (2003) Feeding value of wild Napier grass (Pennisetum macrourum) for cattle supplemented with protein and/or energy rich supplements. Animal Feed Science and Technology 108:15–24. DOI: 10.1016/S0377-8401(03)00167-6

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Friday Fellow: Red Sophronitis

by Piter Kehoma Boll

Orchids are very popular ornamental flowers and come in a variety of colors, sizes and shapes. Finding them in natural habitats is not always that easy, but is not difficult either if you are visiting an area of Atlantic Forest in Brazil.

One orchid species that is native to this endangered biome is Cattleya coccinea, until very recently known as Sophronitis coccinea, a reason why it is still often called Sophronitis among orchid collectors. Even among collectors this species often lacks a common name, but I think “red sophronitis” fits well, although, well… almost all species in the former genus Sophronitis are red.

A specimen of Cattleya coccinea growing around the canyons near the border of the states of Santa Catarina and Rio Grande do Sul, southern Brazil. Photo by João Gava Just.*

Occurring in areas of mid to high elevations from around Espírito Santo southward to Rio Grande do Sul, Brazil, and reaching neighboring areas in Misiones, Argentina, the red sophronitis is a relatively small orchid that produces solitary flowers with a bright scarlet red color. The two petals are much broader than the three sepals, although the labellum, the third tubular petal, is narrower.

Although sometimes mentioned as an endangered species, the red sophronitis is the species in the Sophronitis group with the largest natural population and widest geographical range. One closely related species, the Mantiqueira’s sophronitis, Cattleya mantiqueirae, is in a much more critical situation and was, initially, considered a subspecies of the red sophronitis. Recent molecular analyses, though, questioned the current classification of both species and they may end up becoming again a single species or perhaps be split into more species.

Closeup of the flower. Photo by Naoki Takebayashi.**

The red sophronitis flowers between late winter and early spring, with the peak from August to October. The flower, normally a single one each time, is scentless and lacks nectar. Nevertheless, the conspicuous nature of the flower suggests that the plant is pollinated by a vision-oriented animal. After some observations of flowers in the wild, the only identified pollinator was the hummingbird Chlorostilbon lucidus. The small bird visits the flowers looking for nectar but, not finding any, leaves very quickly, in less than 5 seconds, but this is enough to carry pollen from one flower to another. Bees, which are common pollinators of other species of Cattleya, do not seem to have any interest in this species.

Despite its lovely appearance, the red sophronitis is a liar. It attracts a naïve pollinator promissing some reward but makes the poor creature move away with nothing. But beauty has never been a synonym of kindness despite our human efforts to think so.

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References:

Caballero-Villalobos L, Silva-Arias GA, Buzatto CR, Nervo MH, Singer RB (2017) Generalized food-deceptive pollination in four Cattleya (Orchidaceae: Laeliinae) species from Southern Brazil. Flora 234: 195–206. doi: 10.1016/j.flora.2017.07.014

Rodrigues JF, van den Berg C, Abreu AG, Novello M, Veasey EA, Oliveira GCX, Koehler S (2014) Species delimitation of Cattleya coccinea and C. mantiqueirae (Orchidaceae): insights from phylogenetic and population genetics analyses. Plant Systematics and Evolution 301:1345–1359. doi: 10.1007/s00606-014-1156-z

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