Pink Siris, Sleeping Tree, Persian Silk Tree

2012/05/29 deej 1

Albizia julibrissin, known variously as the pink siris, the Persian silk tree, the sleeping tree, or (incorrectly) as a mimosa, is a common ornamental garden and street tree. It has a graceful, elegant shape reminiscent of a jacaranda or acacia, with smooth light brown or grey bark and feathery, bright green leaves. The tree grows up to 12m tall, with an open, umbrella shaped canopy, providing dappled shade and allowing enough light through for other plants to grow underneath the tree. At night, and during periods of rain, the leaves close up as if the tree is sleeping, leading to the common name ‘sleeping tree’. It is also deciduous, losing all its leaves over the winter even in areas with mild winter temperatures.

The flowers resemble pom-poms of silk threads, which appears to be the origin of the name ‘Persian silk tree’. They have no petals, and consist mainly of a dense cluster of stamens. They are fragrant, light to dark pink, and arranged in loosely branched, pyramidal flower clusters at the ends of the branches. The flowers are attractive to bees, and to nectar feeding birds including hummingbirds. Fruits are flat seed pods 12 – 18cm long, containing light brown, oval-shaped seeds. These pods are gray-brown when mature and remain on the tree into winter. The seeds and foliage may be used as a food for livestock and wildlife, although care should be taken as the seeds may contain some levels of toxic amino acids and saponins.

Silk tree seeds have impermeable seed coats that allow them to remain dormant for many years. One study showed that 90% of the seeds were viable after 5 years. Treatment with boiling water or sulfuric acid decreases the germination time, but germination rates are high even without treatment. Seedlings transplant readily, and are very adaptable. 

Pink siris is found in disturbed areas, including coastal and urban areas. It functions as a pioneer plant; it is drought tolerant, wind tolerant, and will tolerate both salinity and alkalinity in the soil as well as salt spray in coastal areas. It will also resprout strongly when damaged. Pink siris is frost tolerant, but prefers areas of high summer heat. It has been used for land reclamation because of its ability to establish itself on marginal sites. In spite of this, pink siris trees often die at a relatively early age due to fungal diseases (specifically mimosa vascular wilt, a form of fusarium wilt), to which they are susceptible.

A tea made out of the flowers of this tree is used in traditional Chinese and Korean medicine to ward off confusion and dark feelings; a clinical study by Korean physicians found that the methylene chloride fraction of Albizzia julibrissin extract produced an antidepressant-like effect in mice. Further research is needed to verify this effect.

What pink siris trees need:

  • Water – about 1000mm rain or irrigation annually.
  • Sunlight – In its native range, A. julibrissin prefers open sunny ravines.
  • Soil Prefers sandy loam-medium loam soil and can withstand high soil pH and salinity.


What pink siris trees have to offer:

  • Fodder for livestock – the foliage meets the nutritional requirements of cattle and domestic goats, with similar digestibility to alfalfa. In a domestic sheep feeding trial, mimosa digestibility was 61%, and there were no signs of toxicity. The tree tolerates 2 complete defoliations during the grazing season.
  • Nectar for honeybees, other insects, and birds.
  • Erosion and salinity control – Pink siris is cultivated on terrace edges in the Himalayas to prevent soil erosion. It will grow in marginal areas, and tolerates salinity and poor soils.
  • Reclamation and soil improvement – Withstands drought and can adapt well in arid conditions. It is a nitrogen fixing legume, and provides plentiful leaf litter to improve soils.
  • Shade and shelter in the garden.
  • More pink siris trees, which grow easily and quickly from seed.



Images sourced from Wikimedia Commons:

Our First Winter

2012/05/23 deej 0

Winter is here, and the rains have started. Or at least – we had two weeks of rainy weather, and now we have Melbourne winter weather. Cold and dry. It’s lovely for going out in, but my poor baby trees need the wet. K commented the other day that being a permahippy has the unexpected consequence of making you respond to a rainy day with excitement and happiness. So much precious water, so many things that can grow as a result.

The current objective is to extend the tree cover as much as we can before next summer, to provide shade for planting fruit trees, and to start building soil. With that in mind, we’ve been planting seedling trees, which are doing beautifully so far, and we’ve seeded the swale mounds with broad bean (Vicia faba), green lentil (Lens culinaris), and lupin bean (Lupinus spp.) seeds, which are all sprouting. It’s very exciting.

We’ve made (or attempted) a first generation of seed balls, containing some tough, drought tolerant tree seeds (mainly wattles and black locust), pioneer shrubs and groundcovers, and flowers. Flowers for our soon-to-be-established bees, to bring birds and insects onto the property, and just for the joy of flowers – which is, I think, a highly underrated motivation.

The seed ball making wasn’t a complete success. It’s difficult to get red clay powder, or in fact any powdered clay, here so we used bentonite clay which is sold to be dug into garden beds to assist with water retention. It works, but it isn’t ground up very finely, and when you add minerals to it in the form of rock dust it ends up being quite gritty. On top of that, our compost was a little bit gritty as well, with wood fibre in it that hadn’t completely broken down. As a result, our mixture was reasonably granular, and didn’t nucleate as well as I’d hoped. We did make seed balls, but it didn’t go as smoothly as expected.

Lessons for next time? Don’t add rock dust – just sprinkle that out separately on the ground when we broadcast the seed balls. Use the finest clay powder available. Use a more fine-textured compost. I should relax and not be quite such a perfectionist about it.

UPDATE: And after all that, the seed balls worked out fine. We broadcast them last weekend, as well as digging some more swales and starting the Polish swales, and planting another load of tree seedlings.

glass gem corn

2012/05/18 deej 0

The internet – or at least the organic / heirloom gardening, plant-nerd and permaculturish back alleys of it that I frequent – have been buzzing for the last week or so about a newly discovered variety of corn.

It’s called glass gem corn, although it could as easily be called rainbow corn or even omgponies corn. Whatever the name, it’s beautiful.

Glass gem is a flint corn variety, also sometimes called Indian corn (as opposed to dent, or field corn, sweetcorn, and popcorn) which means that it’s used for grinding into cornmeal or cornflour rather than as a fresh vegetable. It might work as popcorn, although it’s not specifically a popping variety. You could probably pick it when it’s still young, and roast it; most grinding corn can be used for roasting as well if you pick it at the right stage of development.

I really, really want to try growing some. Until this week I’d never considered growing a flint or dent corn variety and grinding my own cornmeal, but I’m now fired up to try it. I love tortillas and corn chips, and I’m quite happy to experiment with adding corn to stews and soups the way I’d normally add pearl barley or lentils. I’ve never had grits, but they sound a lot like the South African mealiemeal porridge that my dad used to love, or polenta. Entirely edible.

The only downside is that importing new corn varieties into Australia is quite tricky. Import permits, quarantine inspections, limits on how many seeds can be imported, and then organising those seeds to be grown at a quarantine facility in Australia before quarantine release the resulting plants. I’m not clear on if they even do release the plants, or if they release the seeds of those plants after growing them on for their entire life cycle in a quarantine facility. I’m going to see if I can convince one of the heirloom vegetable seed companies to import some seeds (to grow for more seed, which they can sell next season). Failing that, I’ll have to import some myself.

More Info:

Images via Seeds Trust

Boabs and Baobabs

2012/05/16 deej 0

Most people have barely heard of baobabs, or boabs as they’re more commonly called in Australia. It’s odd, since we’re one of the few places in the world which has a native baobab species – the Australian Boab, Adansonia gregorii.

There are only eight species of baobab. Of the other seven, one is native to Africa (Adansonia digitata, the African Baobab), and the other six (Adansonia grandidieri, Adansonia madagascariensis, Adansonia perrieri, Adansonia rubrostipa, Adansonia suarezensis, and Adansonia za) are endemic to Madagascar.

All baobabs are extremely drought tolerant and hardy. Some are as little as 3m tall, while others are up to 30m in height, but all have massive trunks which can reach 15m in diameter. The massive trunk may be cylindrical, bottle shaped, tapering, or irregular; thick tapering branches resembling a root-system extend from the trunk, which is why baobabs have often been referred to as upside-down trees. The wood is fibrous and soft, under a thick layer of bark, and stores water for dry periods.

The wood can be chewed to provide moisture and relieve thirst; humans as well as certain animals eat it in times of drought. The roots can be tapped for water. The trunk of the tree often develops a hollow, which fills with water during the rainy season and acts as a reservoire during the dry season. Water inside the trunk of a baobab remains potable for months, apparently due to natural preservatives leached by the living wood that keep water from fouling. This may be an adaptation to prevent microbes breeding in the water and infecting the tree, which may have water in the trunk for several months or even years at a time.

Baobabs are semi-deciduous, and may lose their leaves and become dormant for several months of the year. This period depends on the environmental conditions in the area. Under good conditions, growth can be quite rapid, up to 2m in 2 years. Trees will begin producing flowers and fruit after 8 – 25 years, and some species may live for up to 1000 years.

Flowers are large, showy, and highly scented. Although pollinated by fruit bats, the flowers are also a favorite nectar source for bees. The fruit consists of a hard, woody outer shell surrounding an arrangement of segments similar to those of a citrus fruit, with angular pockets of soft pulp surrounding a cluster of hard, black, kidney-shaped seeds. The pulp may be white, yellowish or pinkish in color, and is dry when ripe. It is rich in vitamin C, provitamin A, B complex vitamins (B1, B2, B6), calcium, phosphorus, and iron, and is described as having an acid gingerbread flavour. It forms a mealy solid, but a few hours in the sun dries it into an off-white powder. It can also be beaten into thin, leathery pancakes which can be stored for an extended period. This powdery substance is soaked in water to provide a refreshing drink somewhat reminiscent of lemonade, which is also used to treat fevers and other complaints. The seeds are also reported to be edible.

Each matured plant may produce 30 kg or more of fruit per year. Harvest the fruit when it falls to the ground, or pick ripe fruit if it can be reached. The fruits themselves are unusual in that they remain dangling during the dry season long after the tree sheds its leaves. They are also unusual in remaining edible far past the point where other fruits would have decayed into putrefaction. Stored under normal ambient conditions, they keep for up to 3 months.

Seeds can be collected from picked or fallen fruit. After crushing the hard woody shell of the fruit, the seeds can be extracted from the dry acidic pulp. Baobab seeds have very hard seed coats and germination is usually less than 20%. In nature, dormancy is broken by passage through the digestive system of large mammals. In cultivation, dormancy may be broken by immersing the seed in hot water for five minutes, by manually scarifying the seed coat, or by acid scarification for 6 – 12 hours. Unless pretreated, seeds can take a year to germinate. Seedlings have big, flat and paired cotyledons, and the first leaves are generally narrow, simple and linear. Effective protection against livestock is essential after planting the seedlings.

The leaves (of at least the African Baobab) may be eaten as a green vegetable, sometimes steamed and eaten as a side-dish like spinach, but most often ground up in soups, stews, sauces, relishes, and condiments. They contain high levels of provitamin A. The leaves may be dried, and keep well in this form, without losing their glutinous polysaccharides. To maintain a high level of provitamin A level in dried leaves, it is important not to dry the leaves in the sun. The sprout of a young tree can be eaten like asparagus, and the tap root of very young trees is also edible.


What baobabs need:

    • Water – anywhere from 200 to 1200mm of rain or irrigation per year. Baobabs are very tolerant, and can survive both arid and subtropical climates.


    • Sunlight – Lots of it. Baobabs naturally grow as solitary trees, or as top level canopy trees..


    • Soil They will grow on many different soils, but deep, calcerous soils are best. Baobabs reportedly tolerate laterite as well as relatively alkaline (e.g. limestone) soils.


  • Space – Baobabs are large trees, up to 30m tall and 10 – 15m in trunk diameter. They grow slowly, but wherever you plant a baobab you must plan for it to expend over its lifetime.


What baobabs have to offer:

    • Edible leaves and fruit.


    • Water storage in trunk hollows, and an emergency water supply in the wood itself.


  • Seeds, which can be grown into more baobab trees, either to plant out or for their edible tap roots.


What baobabs do not like:

  • Soggy or waterlogged soils, or even seasonal inundation.


  • Heavy clay soils.


  • Frost (especially when young).



Images sourced from Wikimedia Commons:

Trees and Water

2012/05/15 deej 2

No scheme water, and no bore or rainwater tanks in place, made irrigation over the summer a very labour intensive task. So every weekend we filled up a couple’ve barrels with water and drove them up to Gallifrey, then manually transferred the water to the water tubes around each of the trees using watering cans.

We tried a few water containers, and experiment showed that the recycled plastic olive barrels fitted with taps were the best. The flexible plastic water bladders that we tried first didn’t hold much water, and sprung leaks after two or three uses. The plastic slimline rainwater tank from Bunnings was better, but the lid didn’t seal, and the tap attachment wouldn’t take a regular hose, meaning that we had to siphon water out from the top. Slow.

It could have been worse; our neighbour thought we were manually watering each of the tree seedlings every weekend. The water tube tree guards were a life saver; they’re UV resistant plastic tree guards with a built-in 20L water bladder and a dripper in the base. The water drips out slowly over (in theory) 2 weeks. In hot weather the water in the water tube expands, forcing the drip rate to increase, while in cooler weather and at night when the plant requires less water the drip rate decreases.

So far, we have four fig trees (Ficus carica), all different varieties, two pomegranates (Punica granatum), a natal plum (Carissa macrocarpa), an acerola cherry (Malpighia glabra), two honey locusts (Gleditsia triacanthos), a baby boab (Adansonia gregorii), three kei apples (Dovyalis caffra), and four moringas (Moringa oleifera) planted. Those are the food trees. Yes, boabs count as food trees. There are also two oak trees (Quercus spp., acorns collected from Stirling Gardens in Perth), a dieback resistant jarrah seedling (Eucalyptus marginata) that a friend gave us, a few dozen wattles, mainly Acacia victoria, but also some Acacia acuminata and Acacia pycnantha, a few pink siris (Albizia julibrissin), and one or two black locust trees (Robinia pseudoacacia).

The plan is to plant a shelter belt around the entire perimeter, inside the mandatory firebreak, consisting of thorny natal plum, kei apple, boysenberry (Rubus x boysenberry) and sea buckthorn (Hippophae rhamnoides), as well as fire retardant trees like oaks, maples, sweetgum, hazel and prickly pear. Eventually, it will be a noise buffering fire barrier in the form of a hedgerow. Inside that will be a secondary firebreak, planted with grain and meadow plants in winter, and space loving succulents and vegetables like squash in the summer. Inside that will be the forest, and the house.

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