Porkbush: Definately my plant of the year :-)

Common names: Porkbush, Elephants Food (English); Spekboom (Afrikaans); iNtelezi, isiDondwane,isAmbilane, iNdibili, isiCococo (Zulu); iGqwanitsha (Xhoza).

Portulacaria afra or porkbush is a popular succulent garden plant in use around the world and is often used for bonsai. It has now been shown to be effective in carbon sequestration (binding atmospheric carbon which is responsible for climate change), in semi-arid landscapes and thicket vegetation it is also being used for restoration purposes. Derivation of name and historical aspects The name Portulacaria is composed of Portulaca + aria suggesting a similarity to the genus Portulaca. The word afra is in reference to the fact that the plant occurs in Africa. The porkbush belongs to a large and widespread family (Portulacaceae) which includes the popular Portulaca and is often sold in garden centres and grown in domestic gardens as an annual for summer colour, although this is not a South African species. Other members of this genus include Portulacaria armiana and Portulacaria pygmaea the former has larger grey green leaves and is native to Namibia although it is not often cultivated, whereas the latter is a dwarf succulent shrublet with small, thickly fleshy, grey green leaves and occurs on rocky hillsides in Namaqualand, South Africa. Description The porkbush is an attractive, evergreen succulent shrub or small tree that can reach 2 - 5 m in height, although usually around 1.5 - 2 m in a garden situation. It has small round succulent leaves and red stems. Small star-shaped pink flowers are borne en masse from late winter to spring although flowering in cultivation is often erratic. They are a rich source of nectar for many insects, which in-turn attracts insectivorous birds. Distribution It is found in warm situations on rocky slopes in succulent karoo scrub, thicket, bushveld and dry river valleys in the eastern parts of South Africa from the Eastern Cape northwards into KwaZulu-Natal, Swaziland, Mpumalanga and the Limpopo Province as well as Mozambique. Conservation status Portlulacaria afra is listed in the National Red Data List as Least Concern which indicates that it is not threatened in its natural habitat. Ecology Interesting ecology has been observed with this plant in the Eastern Cape where it forms part of the diet of the Addo elephants in the Addo National Park. Elephants eat the plant from the top downwards allowing the plant to spread itself vegetatively by spreading horizontal branches at ground level. Outside the park the plants are eaten by goats who eat the plant from ground level upwards preventing the plant from spreading vegetatively. Consequently these plants must rely solely on seed to proliferate the species which often proves difficult in such a dry climate. As a result it was observed that inside the park where the plant is subjected to browsing by elephants the pork bush survives and spreads successfully whereas outside the park the plant is becoming sparse as a result of overgrazing and poor regeneration. A very interesting mistletoe, Viscum crassulae, parasitizes this plant. The foliage of this mistletoe is hard and rough in contrast to the soft and smooth leaves of the porkbush. The small red fruits of the mistletoe are enjoyed by birds who eat the sweet outer layer and discard the sticky seed which is normally wiped onto a branch by the bird. There it germinates directly through the bark of the porkbush with specialized roots called haustoria which extract moisture and soil nutrients from the host, while the green leaves allow the semi-parasitic mistletoe to produce its own food. Uses & cultural aspects The leaves of the porkbush can be eaten and have a sour or tart flavour. It is heavily browsed by game and domestic stock and highly favoured by tortoises. The porkbush has also been indicated as a soil binder for preventing soil erosion. Traditional uses also include the increasing of breast milk by lactating mothers. The leaves are used to quench thirst, sucking a leaf is used to treat exhaustion, dehydration and heat stroke. Crushed leaves can be rubbed on blisters and corns on the feet to provide relief. The leaves are chewed as a treatment for sore throat and mouth infections while the astringent juice is used for soothing ailments of the skin such as pimples, rashes and insect stings. The juice is also used as an antiseptic and as a treatment for sunburn. It is also recorded that a small sprig of porkbush steamed with a tomato bredie (stew) imparts a delicious flavour. The honey made from the flowers of porkbush is said to be " unsurpassable in flavour and texture" by one reference (Roberts 1990). The porkbush on Climate Change Recent research has shown the Porkbush to be an excellent 'carbon sponge' as it has the ability to sequestrate (absorb) free carbon from the atmosphere which is used to make plant tissue. Carbon is one of the major greenhouse gases which are responsible for the warming of the earth's atmosphere; it is produced in excess by burning of fossil fuels. Currently, humans are producing atmospheric carbon faster than the environment can absorb it, causing a deficit which remains in the atmosphere and causes heat from the sun to be trapped instead of being radiated back out into space. The porkbush has the unique ability to absorb more carbon from the atmosphere than most other plants and it does so particularly efficiently. A stand of Pork bush consequently has the ability to remove more carbon from the atmosphere than an equal amount of deciduous forest. How does it manage this? The porkbush has the ability to make use of two different photosynthetic pathways, when conditions are favourable it manufactures its food to sustain growth by using the same method (pathway) that most other plants use. However, when conditions are not favourable and other plants have to shutdown and wait for sufficient rain, the porkbush can switch to a different pathway called CAM (Crassualean Acid Metabolism) whereby it can continue to grow and slurp up huge amounts of carbon despite adverse climatic conditions. This allows the plant to excel in the arid or semi-arid conditions that it is native to. Further to its carbon habit, the large spreading shrub covers and shades the soil from the harmful rays of the sun creating a favourable environment under the bush for insects and other wildlife to inhabit, while the dead organic matter which accumulates under the bushes has an enriching effect on the soil. This further enrichment of the soil improves its water-holding capacity which further benefits the porkbush as well as other plants and animals including micro-organisms, which occur in the area. Projects now active in the areas where the porkbush occurs seek to utilize it as a rehabilitation aid to restore over-utilized natural habitats to their formerly productive state. At the same time these sites act as carbon sinks (kind of carbon bank) where carbon can be collected and used where it belongs and is productive to both humans and the environment. Potential earnings through carbon credits could be translated into social upliftment in the areas where this plant is being utilized. Growing porkbush This versatile plant can be used in full sun or semi-shade in dry areas or even in well-watered flowerbeds. It can tolerate a moderate degree of frost, especially when mature. (It is also used as a rootstock for grafting the closely related but more difficult to grow Ceraria namaquensis (Namaqua porkbush) which cannot tolerate water around its roots as it comes from very dry areas). The porkbush can be used as a screen or even a clipped hedge. It also makes a handsome and hardy Bonsai. Various different forms are found in cultivation, most of which originate from the Karoo Desert National Botanical Garden in South Africa (Ian Oliver pers. com.) These forms include a prostrate low growing ground cover, 'Prostrata'; a shrubby form with small round leaves which turn an attractive yellow in full sun, 'Aurea' and 'Foliis variegatus' a slow growing variegated form which is well suited to pot culture. Another variegated form known as 'Medio-picta' has green leaves with whitish markings spreading from the centre. A large-leaved form known as ' Limpopo ' has much larger, more ovate leaves that can measure up to 20 - 30mm long and 15 - 20mm wide. This form represents the northern populations which extend into the northern provinces of South Africa and Mozambique. The porkbush is easily propagated from cuttings, the seed is not often available. Cuttings or truncheons strike root easily and can even be planted directly into the ground where they are to be grown. Alternatively cuttings can be taken in the normal manner and allowed to dry out for a day or two in a cool, dry place and then planted in washed river sand. Keep them in a warm shady position until they are rooted and ready to be planted out. Cuttings root quickly and can usually be planted out after four to six weeks.

Bats form friendships too ...

As Valentine's Day cards attest, humans value love and friendship that aren't just forged by family ties, common interests or sexual attraction. Now researchers have determined that such human-like friendships exist among at least five different types of animals.

Prior studies determined that elephants, dolphins, some carnivores and certain non-human primates, such as chimpanzees, have the ability -- just as humans do -- to maintain enduring friendships in highly dynamic social environments. A new study, published in the latest issue of the Proceedings of the Royal Society B, adds bats to that list.

Female wild Bechstein's bats prefer to literally hang out with certain friends while they also keep loose ties to the rest of their colony. Lead author Gerald Kerth told Discovery News that these bat buddies mirror human ones. Despite all of their "daily chaos, the bats are able to maintain long-term relationships," he said.

"We do not work, play and live together with the same individuals all the time during the day and week," he explained. "But nevertheless, we are able to maintain long-term relationships with our friends and our family despite our often chaotic and highly dynamic social lives."

Kerth, a professor at the University of Greifswald's Zoological Institute, and colleagues Nicolas Perony and Frank Schweitzer monitored colonies of the bats over a period of five years. Male bats of this species are solitary, but females roost together in bat boxes and tree cavities. They preferred certain companions over the years.

In addition to resting together, "colony members exchange information among each other about suitable roosts, make flexible group decisions where to communally roost next, groom each other and profit from communal roosting through warming of each other," Kerth said.

The researchers determined that the female bats did not just select their companions based on size, age, reproductive status or relatedness, although older female bats often maintained links between friend subgroups.

Kerth believes the human-like friendships likely exist among other bats living in temperate zones, since these bats often live in colonies that also frequently split and merge, a phenomenon known as "fission-fusion."

"Fission-fusion dynamics with long-term social relationships are also found in elephants, dolphins, chimpanzees and humans," he said.

Jonathon Balcombe, an animal behavior research scientist and consultant for the Physicians Committee for Responsible Medicine, pointed out that female bats even sometimes serve as midwives.

In one documented case, a pregnant fruit bat in Florida was attended by an unrelated female fruit bat, according to Balcombe, who is author of the book "Second Nature." The helper bat repeatedly groomed and hugged the pregnant bat during the birthing process.

"Following birth, the helper groomed the pup, and she and a third female fanned the mother with her wings," added Balcombe.

Other animals with human-like friendships, such as elephants, tend to have large brains, but bats prove that even species with "peanut-sized brains can also have long-term relationships," Kerth said. "This for me suggests that it does not necessarily take large brains to keep track of relationships in highly dynamic societies."

The discoveries may negate prior theories on why humans evolved large brains and became such a dominant species. Previously, some anthropologists thought this was driven by our need to maintain relationships in an ever-changing social setting. Now it's suspected that other factors must have come into play. In fact, tiny-brained bats may even be better at maintaining friendships than we are.

Kerth said he admires "bats for doing things that I find difficult: making quick and efficient group decisions in a group of 20-plus individuals and keeping social relationships despite a regular mixing of social partners."

"I sometimes feel that this is cognitively demanding for me (since) we all know the embarrassing feeling when we forget the name/affiliation of somebody we haven't seen in a while but who remembers us well," he continued, suggesting that this recently happened to him at a conference.

In the future, he'd like to see if bats ever experience such social faux pas.

Scientists confirm what we already know about elephants?

Contrary to the belief of many scientists (as well as many members of the public), new research confirms that Africa has two -- not one -- species of elephant. Scientists from Harvard Medical School, the University of Illinois, and the University of York in the United Kingdom used genetic analysis to prove that the African savanna elephant and the smaller African forest elephant have been largely separated for several million years.

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"Experimentally, we had a major challenge to extract DNA sequences from two fossils -- mammoths and mastodons -- and line them up with DNA from modern elephants over hundreds of sections of the genome," says research scientist Nadin Rohland of the Department of Genetics at Harvard Medical School.

According to David Reich, associate professor in the same department, "The surprising finding is that forest and savanna elephants from Africa -- which some have argued are the same species -- are as distinct from each other as Asian elephants and mammoths."

Researchers only had DNA from a single elephant in each species, but had collected enough data from each genome to traverse millions of years of evolution to the time when elephants first diverged from each other.

"The divergence of the two species took place around the time of the divergence of the Asian elephant and woolly mammoths," says Professor Michi Hofreiter, who specializes in the study of ancient DNA in the Department of Biology at York. "The split between African savanna and forest elephants is almost as old as the split between humans and chimpanzees. This result amazed us all."

The possibility that the two might be separate species was first raised in 2001, but this is the most compelling scientific evidence so far that they are indeed distinct.

Previously, many naturalists believed that African savanna elephants and African forest elephants were two populations of the same species, despite the significant size differences. The savanna elephant has an average shoulder height of 3.5 meters whereas the forest elephant has an average shoulder height of 2.5 meters. The savanna elephant weighs between six and seven tons, roughly double the weight of the forest elephant.

DNA analysis revealed a wide range of genetic diversity within each species. The savanna elephant and woolly mammoth have very low genetic diversity, Asian elephants have medium diversity, and forest elephants have very high diversity. Researchers believe that this is due to varying levels of reproductive competition among males.

"We now have to treat the forest and savanna elephants as two different units for conservation purposes," says Alfred Roca, assistant professor in the Department of Animal Sciences at the University of Illinois. "Since 1950, all African elephants have been conserved as one species. Now that we know the forest and savanna elephants are two very distinctive animals, the forest elephant should become a bigger priority for conservation purposes."

This research was funded by the Max Planck Society and by a Burroughs Wellcome Career Development Award in Biomedical Science.

The researchers, whose findings appear online in PLoS Biology, compared the DNA of modern elephants from Africa and Asia to DNA that they extracted from two extinct species: the woolly mammoth and the mastodon. Not only is this the first time that anyone has generated sequences for the mastodon nuclear genome, but it is also the first time that the Asian elephant, African forest elephant, African savanna elephant, the extinct woolly mammoth, and the extinct American mastodon have been looked at together.