Calendar
Sep
Sat 15 2 – 4 pm Meeting at Gumnut Hall, Gumnut Place Cherrybrook with guest speaker Andrew Berneutz on “Breeding Australian Plants for Overseas ”
Oct
Wed 10 at 10am Propagation at Bidjiwong Community Nursery
Sat 20 Bushwalk: Darwin’s Walk Wentworth Falls
Nov
Wed 14 at 10am Propagation at Bidjiwong Community Nursery
Sat 24 at 2-4 pm Meeting at Gumnut Hall, Gumnut Place Cherrybrook with guest speaker Michelle Leishman on a Climate Change topic.
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THIS MONTH’S MEETING
Saturday 15 September at 2pm
This month’s meeting is on Saturday 15th September due to a major event falling on our usual 4th Saturday.
Our guest speaker will be Andrew Berneutz talking about
“Breeding Australian Native Plants for Overseas Markets”
Acacia cardiophylla – Wyalong Wattle
This species occurs naturally on the western slopes of NSW from near Dubbo to the West Wyalong area, often on fairly sandy loams on banks of watercourses. It requires good drainage in cultivation, tolerates frost and has low water requirements once established.
The species name means heart-shaped and refers to the shape of the pinnules.
Acacia longifolia Sydney Golden Wattle
The Sydney Golden Wattle is one of the best known native plants of the Sydney district, and is very conspicuous in late Winter and Spring with its masses of golden yellow flower spikes. This shrub or small tree grows from 2 to 4 m tall. Its phyllodes are 8-16 cm long and up to 2 cm wide; most are pointed at the apex. The photo shows the prominent longitudinal veins. The flowers are borne in dense spikes which grow in pairs in the leaf axils – you can see this in the photo also.
This species is naturally widespread from coast to mountains, usually on sandy soil in forest and woodlands. It is generally hardy in cultivation. The perfumed flowers occur from June to November.
Miniscule Fern’s History Gives Promise
The leaves of the fern Azolla filiculoides may be compared to the size of a gnat.
A tiny fern – with each leaf the size of a gnat – may provide global impact for sinking atmospheric carbon dioxide, fixing nitrogen in agriculture and shooing pesky insects from crops.
The fern’s full genome has been sequenced by a Boyce Thompson Institute scientist and his colleagues around the world, as reported in the July issue of Nature Plants.
Azolla filiculoides is a water fern often found fertilizing rice paddies in Asia, but its ancestry goes much further back.
“Fifty million years ago, Earth was a much warmer place. Azolla, this fast-growing bloom that once covered the Arctic Circle, pulled in 10 trillion tons of carbon dioxide from our planet’s atmosphere, and scientists think it played a key role in transitioning Earth from a hot house to the cool place it is today,” said Fay-Wei Li, a plant evolutionary biologist at BTI and the lead author of the work, “Fern Genomes Elucidate Land Plant Evolution and Cyanobacterial Symbioses”
[www.nature.com/articles/s41477-018-0188-8].
Li and senior author Kathleen M. Pryer of Duke University led a group of more than 40 scientists from around the world to sequence the genome completely. Li also is an adjunct assistant professor of biology at Cornell, the host campus to BTI.
As the group sequenced the genome, it identified a fern-specific gene shown to provide insect resistance.
“In general, insects don’t like ferns, and scientists wondered why,” said Li, who explained that one of the fern’s genes likely transferred from a bacterium. “It’s a naturally modified gene, and now that we’ve found it, it could have huge implications for agriculture.”
Nitrogen fixation is the process by which plants use the chemical element as a fertilizer. While plants cannot fix nitrogen by themselves, Li said, the genome reveals a symbiotic relationship with cyanobacteria, a blue-green phylum of bacteria that obtain their energy through photosynthesis and produce oxygen. Special cavities in the Azolla leaf host cyanobacteria to fix nitrogen, while the plant provides sugary fuel for the cyanobacteria.
“With this first genomic data from ferns, science can gain vital intelligence for understanding plant genes,” said Li. “We can now research its properties as a sustainable fertilizer and perhaps gather carbon dioxide from the atmosphere.”
Ferns are notorious for having large genomes, some as large as 148 gigabases3 [c. 150 pg (picograms)], or the equivalent of 148 billion base pairs of DNA sequences. On average, fern genomes are 12 gigabases [c. 12 pg] – a reason why scientists have not sequenced one, until now. The Azolla genome is 0.75 gigabases [c. 0.77 pg].
From: ANPSA Fern Study Group Newsletter July 2018 See Photo Page 7
Acacia – Background
Introduction
Acacia is a genus of around 1000 species, most of which occur in Australia with another dozen or so being found in Asia. Until recently the genus was more broadly described with about 1400 species spread over five sub- genera. This is discussed further below (see “Acacia, Vachellia and Racosperma”).
Acacias occur in all Australian states from coastal zones to mountains to the dry inland. Collectively, acacias are known as “wattles” and one of them, Acacia pycnantha, is the national floral emblem. The green and gold colours of the foliage and flowers has provided Australia’s official colours.
The derivation of the term “wattle” is interesting. “Wattle” is an old English word meaning interlaced rods and twigs. In the early years of the European settlement in Australia, shelters were constructed of flexible sticks woven together and plastered with mud, a technique known as “wattle and daub” and the wood most commonly used came from a plant now called Callicoma serratifolia which became known as “Black wattle”.
Callicoma has Acacia-like flowers but is not closely related to Acacia. However, because of the similarity in flowers, the term “wattle” eventually became associated with all Australian acacias and, even more confusingly, ” Black wattle” is also applied to some Acacia species.
Characteristics
Together with the ‘pea- flowered’ plants and another group which includes Senna and Cassia, acacias are legumes and are able to take-up (“fix”) their nutrient requirements for nitrogen directly from the atmosphere with the aid of soil bacteria (Rhizobium sp).
This occurs in nodules on the roots of the plants, as shown in the photograph.
Australian acacias are generally small to large shrubs but there are a few which become large trees. The individual flowers are very small but are arranged into rod-like or globular heads of a large number of flowers. The colour is almost invariably in the range between white and bright yellow but one solitary species (A.purpureapetala) has mauve flowers and a recently discovered form of the normally yellow-flowered Acacia leprosa has deep pink flowers. This form has been given the cultivar name “Scarlet Blaze”
Many Australians regard the flowering of wattles as signalling the coming of spring and it’s true that many commonly grown species flower in late winter. However, it’s equally true that a wattle can be found in flower somewhere at any time of the year. Following flowering, seeds develop in pods (legumes) which vary in shape between species and may be flat, short, elongated or cylindrical.
In the majority of species, the compound (bipinnate) leaves which appear on all Acacia seedlings are quickly replaced by flattened stalks known as phyllodes, as shown in the diagram.
Phyllodes have a leaf-like appearance and can be enormously variable in size and shape. A few species, such as the well-known “Cootamundra wattle” (A.baileyana) and “Mudgee wattle” (A.spectabilis), retain the compound, fern-like leaves throughout their lives.
Many Acacia species occur in areas where bushfires are common, such as dry forests and woodlands. In these habitats they are often “pioneer” species, quickly recolonizing burnt-out areas and then being gradually replaced by other species in the plant community. They are often helped in this role by ants which store the seeds underground. The seeds themselves usually have a very long viability.
Botanical Classification
The botanical classification of the legumes is a little confusing. In Australia, until recently, most authorities classified them as belonging to three distinct families – Fabaceae (typical ‘pea- flowered’ plants), Mimosaceae (Acacia and relatives) and Caesalpiniaceae (Senna, Cassiaand relatives). However, around the world they have usually been classified in a larger Fabaceae family, with three subfamilies:
- Sub-family Faboideae (typical ‘pea-flowered’ plants)
- Sub-family Mimosoideae (Acacia and relatives)
- Sub-family Caesalpinioideae (Senna, Cassia and relatives).
This later classification now seems to have been adopted by Australian herbaria and is also used on the ANPSA pages. The previous classification into three separate families will still be seen in books and in other websites.
The following table summarises the ‘previous’ and ‘current’ classifications.
| Group | Previous Classification | Current Classification |
| Typical ‘Pea-flowered’ Plants | Family Fabaceae | Family Fabaceae subfamily Faboideae |
| Acacia and relatives | Family Mimosaceae | Family Fabaceae subfamily Mimosoideae |
| Senna, Cassia and relatives | Family Caesalpiniaceae | Family Fabaceae subfamily Caesalpinioideae |
How to grow an Australian grassland
Part 2 – planting & maintenance
from James Beattie gardendrum.com December 19, 2017
This is the second in a two part series about establishing native Australian grasslands in a garden context, specifically for nature strips (aka front verges). (You can find information about why you should grow a suburban native grassland and then preparing your garden here in Part 1 How to grow a native Australian grassland).
Creating a native grassland is a uniquely Australian take on the prairie school of gardening and arguably better suited to the local climate than exotic species . I’m not an indigenous-only gardener by any means, but my work has seen me develop a deep love of native grasses. I use them where I can in my gardens because they have virtues, and precious few others seems to be extolling their usefulness i n developing a prairie style all our own. As Australian gardeners we’re behoved to experiment with our native grasses. They need more devotees! My nature strip is planted almost exclusively with local species, with one exception that I’ll get to later.
One big difference between the prairie school and native grassland plants is their ultimate size. The exotics are big and bold, whereas local grasses are smaller by comparison. This does not mean the locals are less showy, the locals and the exotics share more similarities than differences. Like exotic grasses, local grasses remain ornamental over long periods with seasonal peaks and troughs. Let me stress, they’re more peak than trough! The overall aesthetic is one of great Australian beauty that continually changes with the seasons.
One important distinction with native grasses should be made before plunging head-long into the detail. Native grasses are divided into two categories, roughly speaking, cool (C3) and warm season (C4) grasses, which refer to the time of year they are actively growing. The C3/C4 epithet refers to the carbon dioxide uptake mechanism they use in photosynthesis. I’ve used exclusively cool-season grasses because they grow when rain is reliable and plentiful in Melbourne – I have never and would never turn a hose on my naturestrip! For an excellent explanation and species list of C3 and C4 grasses, see this link.
Having prepared an area for creating a grassland, choosing species is the fun bit. For reasons of brevity I’ve divided the species you can use into three categories, each with their own important function in achieving the look effectively. The first is fillers, the second is forms and the last is features.
Fillers, Forms and Features
You want a filler, a single species to make up the bulk of the grassland. Choosing the right species will depend on a lot of considerations.
The biggest I had was space, my grassland is a small 2.5m X 8.5m naturestrip after all, so I had to choose a very low growing species. I chose kneed wallaby grass as my filler, Rytidosperma geniculatum. It’s a tuftie to about 10-20cm high, flowering at around 30cm. In time as they fill out and competition really gets going they will be much lower, below 10cm and flower just above the foliage. This has already started happening some 3 years into my grassland’s life.
When choosing grasses for form, go for larger tufting species. Both form and filler should make up to 80% of the total planting – the relationship between them is vitally important to the aesthetic. Think of them as groundcover and upright accent plants – there should not be too many of either, a combination of the two that is ‘just right’ to please the eye.
Poa lab for form is a classic and proven performer, though I’ve limited its use to direct foot traffic around my planting, hoping it would deter people from cutting through it. So far it’s worked brilliantly. My main form grass is Poa sieberiana because it doesn’t get as tall as poa lab, roughly about a third to half the size, with a similar habit.
Features is where you really get to let rip with colour. As with all garden design, choosing your mix of colours is important. There are many cool-coloured native flowering species, but just as many hot colours. But hot colours tend to be different shades of yellow in the main, not many local plants provide long periods of orange, a great many fewer still where red is concerned. I chose a mixture of native flax, Linum marginale, and the ever- wonderful billy buttons, Pycnosorus globosus as a contrasting blue/yellow colour scheme. The only non- indigenous plant I used in my grassland was the annual
Western Australian paper daisy, Rhodanthe chlorocephala subsp. rosea. I sow them every year in metal rings I set into the ground. In spring, boy do they put on a show. They have literally stopped traffic in my street.
One important thing to keep in mind with features is that there are also grasses that fall under this category. The spear grasses, Austrostipa spp., are invaluable for seasonal feature. I’ve used Austrostipa rudis subsp. rudis as a seasonal accent and it works brilliantly. It’s a narrow, upright tufting grass with foliage reaching only about 20cm in height, but the glumes it puts up are are 60 – 100cm tall, airy, breeze-catching and showy. I planted it because I wanted the glumes a good head and shoulders above the rest of the plants – it was to act as the ceiling for the planting and it has performed the role very well indeed. Even after it sheds its seed, the glumes are retained for many months of delight, catching breezes and afternoon sun in equal measure.
TUBES -V- DIRECT SEEDING
Whatever mix of grasses and flowering plants you choose an important consideration when it comes to planting is buying tubestock versus direct seeding. There are a number of suppliers* of native grass seed that provide a good range of the ‘filler’ species, and direct seeding as much of these as you can is not only more economical, but the plants themselves will tend to be more robust.
Tubestock has a tendency to do well for a few years, erupting out of the ground, but the phrase living fast and dying young applies to tubes more often than not. They’ve spent their entire lives mollycoddled in tubes at nurseries and once planted out, despite looking great for the first few years, can often give up the ghost well before a plant that’s directed- seeded will.
HOW MANY PLANTS DO YOU NEED?
My strip is 2.5m X 8.5m. I used 110 tubes of ‘form’ and ‘feature’ grasses oversowed with seed of my ‘filler’ species. Plant densely to crowd out unwanted weeds. I always over-plant as grasses are very good at self-thinning down the track. Have at least 5 plants per square metre.
The economics of directing seeding are another argument in its favour. To fill out an area the size of my grassland, I’d need at least 100 tubes of my filler species, kneed wallaby grass. At around $3.50 a pop, costs begin to approach preclusive. A 250g bag of kneed wallaby grass seed was more than enough to cover my naturestrip (front verge) – after killing off the grass in autumn I just raked the grass and soil over and broadcast it everywhere. It germinated prolifically and continues to fill out wonderfully.
Where form and feature plants are concerned, tubes will do the trick. Many of these species will self-seed well, so if the original plants die it’s not a big deal. Poa lab can be replaced and will give you a good clump in 12 months or so.
MULCH OR NO MULCH – RECRUITMENT
The term recruitment is just another word for self- seeding. Mulch will significantly impede the recruitment of grasses and flowering plants in grassland settings. Mulch also breaks down and adds nutrients to the soil – this is a significant consideration in ongoing weed management in grasslands.
Mulch will not do them any favours!
Many native grassland plants have adapted to grow in nutrient- poor soils, the kind of soils that a lot of problem weeds find it difficult to get a foothold in, especially once grasses become well-established. This ecological characteristic can inform smart ongoing weed management with a great deal of success.
It’s almost counter- intuitive not to mulch, every gardening resource has told us for years that mulch is invaluable for retaining moisture and protecting soil, and it is all true in the right context.
Native grasslands in the natural style I’ve planted mine are not the right context. If I used mulch I would have enjoyed nowhere near the amount of recruitment that’s gone on. The native flax, Linum marginale, went from 20 tubes in their first year to literally thousands of seedlings over the ensuing two years, creating great drifts of blue in springtime. Their seed ripens in early summer, is shed and sits waiting until the cool months return before doing it all over again.
The same goes for the spear grass and the wallaby grass I used. One the most enjoyable things about growing grasses in this naturalistic style is watching the ecology evolve over time. From the original tubes of spear grass there have popped up many more in areas I thought they might struggle to gain a foothold. This is particularly beneath the brush box street tree that’s smack-bang in the middle of the planting. In late spring and summer the tree’s trunk is clothed in swords of spear grass glumes, it’s delightful. Grasses are great niche-fillers and will readily spread themselves around areas they find the most hospitable.
However, if you wanted to go for a more stylised planting, keeping different species in blocks of textures, then mulching would certainly be appropriate.
Maintenance and biomass reduction
Once you’ve prepped, sowed and planted the battle against weeds should begin straight away. The price of a good- looking grassland is eternal vigilance. In the first 12 to 18 months be prepared to do a lot of hand- weeding. This first establishment phase is critical, as once you begin to get a good coverage of grass the weeds naturally reduce in number, becoming easier to spot and pull out.
If you’re down there pulling weeds and checking things out you’ll quickly learn the difference between weedy grasses and the locals. For those worried about identification of young plants, you can leave them until they begin to mature and flower, by which stage there’ll be little doubt as to their identity. A good rule of thumb for beginners in this respect is that local grasses, even young plants, tend to have easily distinguishable hairs on the blades, whereas many of the weedy grasses do not.
A major undertaking in grasslands at least once a year is biomass reduction. By the end of summer there will be a lot of dried up glumes and thatch dagging a bout. This coverage needs to be dealt with. Back in the day grasslands would be burnt by indigenous people to regenerate them. The good news for the non-pyromaniacal is that the same effect can be achieved with a brush cutter or a high mow-and-catch.
My grassland takes me about half an hour to give it a low brush cut in late summer, just before the cool weather arrives and growth starts to get going again.
A slow, cool burn is the key.
Seeing as we’re talking about fire, you can use it under extreme caution as a tool in your weed management arsenal. I used it successfully this year in my strip after noticing that a particularly pernicious annual weedy silvergrass, Vulpia spp., appeared in alarming numbers.
Fire was highly successful at controlling it. Flame will not kill local grasses but it’s a proven method for dealing with problem annuals. The trick to burning is getting your timing right and this is mainly experiential. Never burn in hot, windy weather. Aim for a slow, cool burn when the weather is amenable, either in spring after the first flush of seed or use a weed burner to spot-burn young annuals as they appear in late winter/spring. Do not burn your grassland at the end of summer when there’s an abundance of dry material – it will burn extremely fast and hot, which isn’t ideal both ecologically- speaking and from a safety point of view.
Native grasslands are a very beautiful thing and once you get them running they are really very easy to look after, it’s getting them to that point that can be a hard slog! But like any great garden it is worth a thousand hours of effort to achieve. While mine is still only in its infancy I’ve already drastically reduced the amount of time I spend maintaining it, and it looks fabulous for months on end and changes with every passing week. Being the creator of an emerging ecology is a very satisfying experience, and there’s immense enjoyment to be had with grasslands on that front alone. I dare you to give it a go!
Victorian APS Event
Showcasing Goodeniaceae at the
12th FJC Rogers Seminar to be held in Horsham, Victoria 20-21st October.
For details visit: apsvic.org.au/fjc-rogers-seminar
Keynote speaker Dr Kelly Shepherd, Senior Research Scientist based in Perth, whose interests include the ‘salt-loving’ samphires.
Guest speaker Brendan Lepschi from Australian National Herbarium talking about his interests in Melaleuca, Santalaceae and Goodeniaceae. Guest speaker Neville Walsh, Senior Conservation Botanist at Royal Botanic Gardens Victoria.
Sunday includes garden tours to Wartook Gardens
Parramatta and Hills District Group
SECRETARY: Caroline Franks
Email: apsparrahills@gmail.com