Category Archives: Botany

Friday Fellow: Golden Wattle

by Piter Kehoma Boll

If you walk through eucalyptus forests in eastern Australia, you may find today’s fellow in its natural environment. Its name is Acacia pycnantha, commonly known as the golden wattle and, as obvious by its scientific name, is a species of acacia.

A golden wattle among eucalyptus trees in southern Australia. Photo by David Muirhead.*

The golden wattle is a peculiar tree. It reaches a height of about 8 m, although most individuals grow only up to 6 m. As common among Australian species of the genus Acacia, the golden wattle does not have true leaves. Instead, it has modified leaf stems, called phyllodes, that are widened to look and function like leaves. The phyllodes have a lanceolate and falcate shape, i.e., they look like a typical leaf that is slightly curved to one side, like a sickle. The outer side of this “sickle” has an extra-floral nectary, a structure that produces nectar and attracts insects and birds that feed on it.

Phyllodes of the golden wattle with the extrafloral nectary seen as a small round protuberance. Photo by Wikimedia user Melburnian.**

The plant produces flower buds all year round but only those produced between November and May will develop further and open between July and November of the next year. The flowers occur in inflorescences and have a strong yellow color and the typical fluffy aspect of acacia flowers caused by the very long stamens.

One inflorescence with several flowers and their very long stamens. Photo by Patrick Kavanagh.***

Despite the huge amount of flowers that a single tree produces, this species is self-incompatible, meaning that it cannot fertilize itself and needs its pollen to be taken to the flowers of another individual of the same species. It has been shown that birds are very important pollinators of the golden wattle and the tree uses the extra-floral nectaries to aid that. When a bird visits the tree, it feeds on the nectar from the extra-floral nectaries and, in the process, brushed against the flowers, becoming covered with pollen. When the birds visit the next tree and brush against its flowers, part of the pollen of the first plant passes to the flowers of the second one.

The bark of the golden wattle produces large quantities of tannins, more than any other Australian acacia, which led to its cultivation for this purpose. When stressed, the trunk exudes a gum (resin) that is similar to the gum arabic produced by African species of acacia.

Gum exuding from the trunk of the golden wattle. Photo by Patrick Kavanagh.***

The golden wattle has been introduced in several other countries, especially in Europe and Africa, for ornamental or economic purposes. In South Africa, its cultivation for tannin production made it spread quickly through the native ecosystems, becoming invasive. And now, as always, we have to deal with the consequences of our irrational acts and run to solve this problem.

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References:

Hoffmann JH, Impson FAC, Moran VC, Donnelly D (2002) Biological control of invasive golden wattle trees (Acacia pycnantha) by a gall wasp, Trichilogaster sp. (Hymenoptera: Pteromalidae), in South Africa. Biological Control 25(1): 64–73. 10.1016/S1049-9644(02)00039-7

Vanstone VA, Paton DC (1988) Extrafloral Nectaries and Pollination of Acacia pycnanthaBenth by Birds. Australian Journal of Botany 36(5): 519–531. doi: 10.1071/BT9880519

Wikipedia. Acacia pycnantha. Available at < https://en.wikipedia.org/wiki/Acacia_pycnantha >. Access on 9 August 2019.

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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 2.0 Generic License.

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Friday Fellow: Chinese Banyan

by Piter Kehoma Boll

With today’s post, I intend to start a series of three Friday Fellows that are connected. After all, that’s what life is, right? Organisms interacting.

So to start, let’s talk about a magnificent tree today, the fig tree Ficus microcarpa, commonly known as Chinese banyan, Malayan banyan, Indian laurel, curtain fig, gajumaru and many other names. Its native range goes from China to Australia, including all the southeastern Asia and several Pacific islands in the way. However, it can be found in many other countries today as it has become a somewhat popular ornamental plant.

A Chinese banyan at the Maui Nui Botanical Garden, Hawaii. Photo by Forest and Kim Starr.*

In its natural tropical habitat, the Chinese banyan reach a height of 30 meter or more, with a crown spreading across more than 70 meters and a trunk more than 8 m in thickness. Most trees are smaller, though, and they never reach such an astonishing size in temperate climates. Its bark has a light gray color and its leaves are smooth, entire, oblanceolate, and about 5 to 6 cm long. Its figs are considerably small, hence the name microcarpa (small-fruited). It is common for large specimens to produce aerial roots, which grow from the branches and touch the soil, forming an intricate and beautiful system.

A specimen with many aerial roots. Photo by Forest and Kim Starr.*

As typical among fig trees, the Chinese banyan is pollinated by a fig wasp, in this case the species Eupristina verticillata. Outside of its native range, the tree can only produce viable seeds in the presence of the wasp, so the insect must be introduced along with it. Its fruits are very attractive to birds, who spread its seeds in their feces. After passing through a bird’s gut and reaching the outer environment again, the seeds attract ants, which spread them even further. Being quite versatile regarding the substrate to germinate, the Chinese banyan can grow on a lot of surfaces, often sprouting through crevices on walls and sidewalks and breaking them as it grows.

Leaves and fruit. Photo by Forest and Kim Starr.*

The Chinese banyan is used in traditional Chinese medicine to treat a variety of conditions, including pain, fever, flu, malaria, bronchitis and rheumatism. Laboratory studies have isolated anti-cancer, antioxidant and antibacterial compounds from the bark, leaves, aerial roots and fruits, as well as anti-fungal compounds from its latex. The tree has, therefore, the potential to be used for the development of many medicines.

A seedling growing on a wall. Photo by Forest and Kim Starr.*

Due to its impressive size and the intricate labyrinth formed by its network of aerial roots, the Chinese banyan tree has an important role to many religious groups in its native range, being often considered the house of spirits, either good or bad ones and its presence usually marks places of worship. Regardless of these beliefs, though, this magnificent tree deserves the admiration that it gets.

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References:

Ao C, Li A, Elzaawely AA, Xuan TD, Tawata S (2008) Evaluation of antioxidant and antibacterial activities of Ficus microcarpa L. fil. extract. Food Control 19(10): 940–948. doi: 10.1016/j.foodcont.2007.09.007

Chiang YM, Chang JY, Kuo CC, Chang CY, Kuo YH (2005) Cytotoxic triterpenes from the aerial roots of Ficus microcarpa. Phytochemistry 66(4): 495–501. doi: 10.1016/j.phytochem.2004.12.026

Kaufmann S, McKey DB, Hossaert-McKey M, Horvitz CC (1991) Adaptations for a two-phase seed dispersal system involving vertebrates and ants in a hemiepiphytic fig (Ficus microcarpa: Moraceae). American Journal of Botany 78(7): 971–977. doi: 10.1002/j.1537-2197.1991.tb14501.

Taira T, Ohdomari A, Nakama N, Shimoji M, Ishihara M (2005) Characterization and Antifungal Activity of Gazyumaru (Ficus microcarpa) Latex Chitinases: Both the Chitin-Binding and the Antifungal Activities of Class I Chitinase Are Reinforced with Increasing Ionic Strength. Bioscience, Biotechnology and Biochemistry 69(4): 811–819. doi: 10.1271/bbb.69.811

Wikipedia. Ficus microcarpa. Available at < https://en.wikipedia.org/wiki/Ficus_microcarpa >. Access on June 8, 2019.

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Looking like lichens: leaves disguised as tree trunks to avoid being eaten

by Piter Kehoma Boll

We are all familiar with animals of many species that developed interesting mechanisms to avoid being eaten. This includes, for example, animals that look like plant parts:

The famous giant leaf insect, Phyllium giganteum. Photo by Bernard Dupont.**

and animals that merge with the background:

An East African jackal, Canis mesomelas, in the Savanna. Can you spot it? Photo by Nevit Dilmen.***

There are also animals that look like other, unpalatable or dangerous, animals, in order to push predators away:

The edible viceroy butterfly Limenitis archippus (top) mimicks the poisonous monarch butterfly Danaus plexippus (bottom). Credits to Wikimedia user DRosenbach. Photos by D. Gordon E. Robertson and Derek Ramsey.***

But we rarely think that plants also use this sort of mechanisms to avoid being eaten. There are, however, some recorded cases of similar behaviors in plants. One case is that of the plant Corydalis benecincta, whose leaves commonly have the brownish color of the surrounding rocks:

The leaves of Corydalis benecincta look like the rocks found in its natural habitat. Photo extracted from http://www.svenlandrein.com/yunnancollections/10CS2204.html

Recently, a study on plants of the genus Amorphophallus found another interesting case of mimicry. This genus, which includes the famous titan arum, usually develops a single large leaf that in some species can attain the size of a small tree or shrub. Such a gigantic leaf seems to be a perfect meal for some herbivores but, to avoid them, many species of this genus developed a series of marks along the petiole of their leaf that look like lichens or cyanobacteria.

Cyanobacteria-like marks on the petiole of Amorphophallus gigas (A); Cyanobacteria-like plus lichen-like marks also on A. gigas (B); And lichen-like marks on A. hewittii (C) and A. dactylifer (D). Extracted from Claudel et al. (2019).

With this mimicry, the petioles, which are quite tender, end up looking like a hard and old trunk that does not look that interesting as a meal for most herbivores. The lichen marks are so well represented that they can even be associated with real lichen genera. For example, the marks seen on the figures B and C above look like lichens of the genus Cryptothecia.

Lichen of the species Cryptothecia striata, which seems to be mimicked by the marks in Amorphophallus gigas and A. hewittii. Photo by Jason Hollinger.*

How and why this marks evolved across Amorphophallus species is still not well understood. Despite the hypothesis that they help the plant mimic a tree trunk, some species with small leaves also have those marks, while some with large leaves do not have any marks or have them in simpler patterns. The titan arum Amorphophallus titanum is a good example of the latter:

Amorphophallus titanum is the largest species of Amorphophallus but displays a considerably simple lichen-like pattern. Photo by flickr user Björn S.**

For a long time, plants were regarded as less dynamic organisms than animals, but in recent years our knowledge about them is increasing and showing that they are actually very versatile creatures that developed similar creative and complex strategies.

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Reference:

Claudel C, Lev-Yadun S, Hetterscheid W, & Schultz M 2019. Mimicry of lichens and cyanobacteria on tree-sized Amorphophallus petioles results in their masquerade as inedible tree trunks. Bot J Linn Soc 190: 192–214.

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*Creative Commons License This work is licensed under a Creative Commons Attribution 2.0 Generic License.

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

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Friday Fellow: Imperial Fritillary

by Piter Kehoma Boll

Let’s bring a high dose of beauty into today’s Friday Fellow with a wonderful species that may sometimes be found in your garden.

Imperial fritillary growing in its natural environment in Kurdistan. Photo by Wikipedia user A2raya07.*

Fritillaria imperialis, the imperial fritillary or crown imperial, is native from Asian highlands between Turkey and the Himalayas but is cultivated worldwide, having a series of artificially selected cultivars. The plant reaches a height of about 1 m and has a series of lance-shaped leaves along its stem, similarly to what is found in other species of the lily family, Liliaceae, to which it belongs. The flowers appear in a whorl close to the top of the stem and face downwards. A crown of small leaves tops the flowers, hence its name imperialis. The bell-shaped flowers are usually orange in the wild but, in cultivars, they vary between red and yellow.

A cultivar named ‘Rubra Maxima’. Photo by Hendry Heatly.**

The imperial fritillary has been used in traditional medicine for centuries by people living around its native range. Recent studies revealed that the plant contains a series of alkaloids, mostly anticholinergic steroidal alkaloids, which have the potential to be used for the development of new medicines to treat several conditions.

Despite its popularity as an ornamental plant, wild populations of the imperial fritillary are endangered in many countries in which it occurs, especially due to habitat loss. In order to aid in the preservation and restoration of wild populations, some laboratory techniques have been developed to generate clones that could help increase population size in the wild.

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References:

Akhtar MN, Rahman A, Choudhary MI, Sener B, Erdogan I, Tsuda Y (2003) New class of steroidal alkaloids from Fritillaria imperialis. Phytochemistry 63: 115–122. doi: 10.1016/S0031-9422(02)00569-1

Gilani AH, Shaheen F, Christopoulos A, Mitchelson F (1997) Interaction of ebeinone, an alkaloid from Fritillaria imperialis, at two muscarinic acetylcholine receptor subtypes. Life Sciences 60 (8): 535–544. doi:
10.1016/S0024-3205(96)00691-1

Kiani M, Mohammadi S, Babaei A, Sefidkon F, Naghavi MR, Ranjbar M, Razavi SA, Saeidi K, Jafari H, Asgardi D, Potter D (2017) Iran supports a great share of biodiversity and floristic endemism for Fritillaria spp. (Liliaceae): A review. Plant Diversity 39(5): 245–262. doi: 10.1016/j.pld.2017.09.002

Mohammadi-Dehcheshmeh M, Khalighi A, Naderi R, Sardari M, Ebrahimie E (2008) Petal: a reliable explant for direct bulblet regeneration of endangered wild populations of Fritillaria imperialis L. Acta Physiologiae Plantarum 30(3): 395–399. doi: 10.1007/s11738-007-0126-2

Wikipedia. Fritillaria imperialis. Available at < https://en.wikipedia.org/wiki/Fritillaria_imperialis >. Access on 11 February 2019.

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Whose Wednesday: Carl Linnaeus the Younger

by Piter Kehoma Boll

Carl Linnaeus is certainly one of the most famous naturalists in history. His son, though, whose birthday we celebrate today, is not as famous and had a complicated and short life compared to his father.

Carl Linnaeus, the son, was born on 20 February 1741 in Falun, Sweden. He received his father’s name and is usually known as Linnaeus filius. His father always wanted him to follow his steps as a botanist and was so eager to do it that he had him enrolled at the University of Uppsala at the age of nine. Linnaeus’ best students, Pehr Löfling, Daniel Solander and Johan Peter Falk, were selected to teach Linnaeus filius.

Portrait of Carl Linnaeus filius by Jonas Forsslund.

Linnaeus filius did not seem to be very interested in following his father steps, though, and was not the best student at all. He never received an academic degree but, due to his father’s recommendations, was hired as a botanical demonstrator at the Botanical Garden in Uppsala when he was only 18 years old. Linnaeus hoped that this opportunity would make his son more interested in botany. During this time, Linnaeus filius described several new plant species.

In 1962, when Linnaeus retired, he was honored to choose his successor. His first choice was Daniel Solander but he declined because he had been appointed to the British Museum in London. Linnaeus’ second choice was Linnaeus filius, and thus he entered the University of Uppsala as head of Practical Medicine even without having the required academic degree. This caused resentment among his colleagues. And the situation became worse in 1963 when Prince Gustav (later King Gustav III) conferred a doctor’s degree of honor to Linnaeus filius.

In 1777, Linnaeus filius was promoted to professor. In the same year, his father, who was very debilitated, decided that his son would not inherit his large herbarium because he was never interested in botany. After Linnaeus the father’s death in 1778, the herbarium remained with his wife Sara Elisabeth. This later forced Linnaeus filius to write an acknowledgment of debts to his mother to receive access to the collection.

In 1781, Linnaeus filius took a two-year trip to visit England, France, The Netherlands and Denmark. In London, he acquired jaundice and shortly after returning home he suffered from fever and had a stroke, from which he died on 1 November 1783, aged 42.

Linnaeus filius did not have children. As a result, the name Linnaeus, created by his grandfather, died out after only three generations.

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References:

Naturhistoriska riksmuseet. Carl Linnaeus fil. Available at < http://www2.nrm.se/fbo/hist/linnefil/linfil.html.en >. Access on 19 February 2019.

Wikipedia. Carl Linnaeus the Younger. Available at < https://en.wikipedia.org/wiki/Carl_Linnaeus_the_Younger >. Access on 19 February 2019.

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Friday Fellow: Leatherleaf Fern

by Piter Kehoma Boll

Leia em Português

You may have seen parts of today’s fellow at least once in your life, as it is a very popular plant in flower arrangements.

A flower bouquet including leaves of Rumohra adiantiformis.

Rumohra adiantiformis is how it is known by botanists, and common names include leatherleaf fern, seven-weeks fern and iron fern. This fern species is widely distributed in Australasia, southern Africa and the Neotropics, as well as several islands of the Pacific Ocean.

Living in forested areas, especially where there is not too much shade, the leatherleaf fern has a biology that is not very different from that of other ferns. It usually grows on the soil, although it may eventually occur on rocks or on trees. What makes this fern special is that its mature fronds are somewhat hard and, after being cut off, continue to have a green and live appearance for a very long time, usually several weeks. This amazing resistance to wilt makes it an ideal species to be used in flower arrangements.

Leatherleaf fern growing in South Africa. Photo by Wikimedia user JMK.*

Currently, most of the leatherleaf fern’s production for commercial use occurs in the state of Florida, USA, where it is cultivated in irrigated shaded nurseries. Other large producers are South Africa and Brazil, especially southern Brazil, but in these two countries the plant is exploited through extractivism, i.e., it is harvested in the wild and not cultivated. Although the extraction of the leatherleaf fern is a widespread activity in both South Africa and southern Brazil and is a major source of income for many families, it is illegal under national or regional laws. However, at least in southern Brazil, where the leatherleaf fern occurs in the highest recorded densities in the world, the main reason for its populations to be diminishing does not seem to be its extraction but rather natural forest succession. As forests grow older and become darker, they become unsuitable for the leatherleaf fern to grow.

It is, of course, necessary to establish limits for its harvest. Otherwise, its increasing demand in the florist market may end up causing concerning effects on its occurrence. The best alternative continues to be cultivating the fern, as it protects wild populations and allows the harvest of high-quality fronds and a faster recovery after defoliation.

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References:

Geldenhuys CJ, van der Merwe CJ (1988) Population structure and growth of the fern Rumohra adiantiformis in relation to frond harvesting in the southern Cape forests. South African Journal of Botany 54(4): 351–362.

Milton SJ (1987) Growth of Seven-weeks Fern (Rumohra adiantiformis) in the Southern Cape Forests: Implications for Management. South African Forestry Journal 143: 1–4.

Souza GC, Cubo R, Guimarães L, Elisabetsky E (2006) An ethnobiological assessment of Rumohra adiantiformis (samambaia-preta) extractivism in Southern Brazil. Biodiversity and Conservation 15: 2737–2746. doi: 10.1007/s10531-005-0309-3

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Friday Fellow: Toothed Micrasterias

by Piter Kehoma Boll

Leia em Português

A new year is beginning with Friday Fellow, and we are going to start small with a lovely tiny alga named Micrasterias denticulata, or the toothed micrasterias as I decided to call it. Found in freshwater habitats, especially peat bogs with acid water, all around the world, this species belongs to the order Desmidiales, which is characterized by its peculiar cell anatomy.

As most desmids, the toothed micrasterias is a single-celled organism and its cell is divided into two halfs, called semi-cells, which are united by a narrow isthmus. Each semi-cell contains a large chloroplast, and the nucleus lies within the isthmus. Due to its symmetrical cell with a well-defined shape, including a series of lobes, the toothed micrasterias and other species of its genus are ideal organisms for the study of cell morphogenesis.

Recently, Micrasterias denticulata has been used to study the effect of several environmental variables, especially pollutants and nutrients, on cell shape. Such studies are important to understand the effects of environmental changes caused by human activities, such as agriculture and waste production, on freshwater ecosystems. Living in an environment that changes constantly regarding pH, salinity and temperature, the toothed micrasterias is a tough organism and has developed mechanisms to avoid intoxication, such as crystalization of heavy metals to make them innactive inside the cell.

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References:

Affenzeller MJ, Darehshouri A, Andosch A, Lütz C, Lütz-Meindl U (2009) Salt stress-induced cell death in the unicellular alga Micrasterias denticulata. Journal of Experimental Botany 60(3): 939–954.
https://doi.org/10.1093/jxb/ern348

Niedermeier M, Gierlinger N, Lütz-Meindl U (2018) Biomineralization of strontium and barium contributes to detoxification in the freshwater alga Micrasterias. Journal of Plant Physiology 230: 80–91.
https://doi.org/10.1016/j.jplph.2018.08.008

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