Monday, 30 July 2007

#24 Pretty Peas

The Hunter Valley is not known for its wildflowers, but considering few significant stands of valley floor native vegetation have escaped clearing, it is not surprising that flowering shrubs and herbs are scarce. But for those wishing to observe our local native blooms, scattered splashes of colour survive, but unfortunately, do not prosper.

Oxylobium pulteneae - Wiry Shaggy Pea is possibly the prettiest pea flower I have found in the Hunter. The short terminal clusters of bright orange flowers were hard to miss, even amongst rampant grasses. Short narrow green leaves are mostly arranged in whorls of three. Most noticible is the downiness of the sepals. Flowering period is October to November. More details at PlantNET.

Pea-flowered plants are legumes and belong to family Fabaceae, which is the third largest in the plant kingdom after the orchid and daisy families. Most leguminous plants develop root nodules in association with Rhizobium bacteria and are capable of converting atmospheric nitrogen into more complex nigrogenous compounds. The wattles (Acacia) and the sennas (Senna) and their relatives are also legumes.

Reproduction and regeneration

Environmental needs of native pea-flowering plants are complex, and on-going study will shed further light on the specialised needs of various species. A brief and simple description of the structure of pea flowers can be viewed here.

Oxylobium ilicfolium - Native Holly or Prickly Shaggy-pea has particularly attractive 'holly-shaped' foliage and neat growth habit. This plant is reasonably common on poor soil in small pockets of unmaintained scrub and roadsides. Flowering season is September to November. More details at PlantNET.

The pea flowers generally consist of understory shrubs, herbs and trailing plants in a range of habitats. Habitat loss as a result of urban and rural development is a major threat to the survival of native plant communities in the Hunter Valley.

Other threats include weed invasion, nutrient enrichment of soil due to agriculture and fertilisation practices, disturbance by vehicles and rubbish, along with failure to implement appropriate fire regime required by some species.

Roughly half of the Fabaceae genera are predominately fire sensitive (eg. Dillwynia, Pultenaea) with the remainder able to resprout following fire (eg. Daviesia, Bossiaea).

Indigofera australis - Native Indigo is also an often seen roadside plant with showy pink to lilac racemes sprouting from leaf axil. It is a spindly bush to a metre or more in height that sways in the breeze, and flowers from August to September. More details at PlantNET.

Some legume species have a release mechanism which ejects seed from mature pods a small distance from the plant (eg. Daviesia, Kennedia, Hardenbergia), while other species have a passive release mechanism whereby seeds are dropped directly to the ground.

Fabaceae generally have hard seeds that dry out during ripening and become impermeable to water. Most have long-lived seedbanks stored in the substrate. Some seed dormancy can only be broken by fire, which creates restrictions on germination due to the inappropriate implementation of fire regime locally. Here is some interesting and easy-to-read observations regarding fire and Australian natural environments. There is more here.

Jacksonia scorparia - Dogwood makes an attractive display of weeping yellow, leaf-less shrubs up to two or three metres high, in October and November. If you are lucky enough to see them massed, they are beautiful. They often grow where run-off water occasionally collects. More details at PlantNET.

Not only do many legume species rely on heat and/or smoke from fire to break seed dormancy, but many plants do not reach sexual maturity until between three and five years, therefore, if fire occurs too frequently, plants do not have the opportunity to produce seed.

Numerous insects are associated with legumes during flowering and fruiting. Pollinators include native and introduced bees, wasps, beetles and flies. Certain beetle seed predators appear to be totally dependant on legumes for their survival. Ants are thought to be important distributors of seed amongst the peas.

Kennedia rubicunda - Dusky Coral-pea is a robust climber and I was pleasantly surprised to find this plant with large red pea flowers scrambling over shrubs, weeds and rocks. The 4cm-long flowers hang in an eye-catching display. As with all Kennedia species, leaves are arranged in threes. Its main flowering period is between July and November. More details at PlantNET.

All the peas I'm featuring here were photograhed in the Broke/Wollombi regions of the Hunter Valley on roadside areas that escaped council slashing due to hilly or rocky terrain.

Daviesia ulicifolia - Gorse Bitter-pea. Although the yellow and brown flowers on this low rounded shrub are small, I found it an interesting plant with its small rigid sharply-pointed leaves. It flowers from August to November and has several subspecies. More details at PlantNET.

Many of Australia's native plants have prickly foliage. Presumably this protects young plants from being grazed by native animals. During my bushland rambles, I have noticed that peas are no exception to sharp and stiff leaves. I find these to be some of the most interesting plants I encounter.

PlantNet has a comprehensive list of Australian pea-flowering plants with information and photographs.

Hardenbergia violacea - Purple Twining-pea is a common and vigorous ground-cover that trails through the undergrowth, over rocks and roadside banks. This plant has been adapted well to home garden use. It has broadly ovate strongly veined leaves up to 9cm long and conspicuous racemes of violet flowers with yellow centres. Flowering period is mainly July to October. More details at PlantNET.

So keep a look out for these little beauties of the Australian bush blooming in a rainbow of colours from late winter to early summer. This is just a small sample of what's on offer for those nature observers with a keen eye. They are fascinating plants with complex lives and interesting habits. They can also be very pretty. Enjoy them!


Anonymous said...

Lovely work HV.

Your blogs are a pleasure to read.


Gaye from the Hunter said...

hi Headsie,

thank you. I will be looking forward to visiting the Goulburn River National Park (western edge of the Hunter Valley) early this spring to investigate the native flora in the sandstone country. I know it won't measure up to the sandstone country flora of the Central Coast that I visited last season, but it will be an interesting excursion.


Denis Wilson said...

Hi Gaye

Lovely photos, especially of the Kennedeya rubicunda. You really got that nicely. Your country is obviously starting to warm up.

No Pea flowers here, yet. Just some of the early Wattles (Sunshine Wattle, A. terminalis is very showy, and A soavolens - the Sweet-scented Wattle).
Late July, early August is about the dullest period of the year, here. I cannot wait for the Spring flowered Orchids to start.


Gaye from the Hunter said...

hi Denis,

all the photos I featured in this blog were taken last spring. I have made an early blog highlighting these little beauties hoping that locals might be enthused to check out some of the Hunter Valley flora as it begins to bloom.

I am also looking forward to seeking out some spring orchids.

I have re-structured this "Pretty Peas" post since you read it, hoping it is now better organised. I took the lead from an excellent wildflower entry from a Western Australian friend's nature blog:


Pete said...

Nice work yet again Gaye, it has been a little while since I've visited your blog and I see it has developed into a very good resource which I find to be most informative.

I note that you mentioned ants playing a role in dispersing the seeds of many legumes. I believe it is the aril found on these seeds that the ants are after as a food source and since they can't remove it from the seed, they carry the whole lot down into their nest.

I see you have included Indigofera australis amongst your plant list and I really like that as it is one of my favourite natives. Many of the old references I've come across use the common name of Austral Indigo and I believe it was used as a source of fabric dye in the early days of settlement. It is quite prolific around here and is the one plant many of my non-plant loving friends have asked me about when out walking and all say what a lovely looking plant it is. I wonder why it isn't common in cultivation and I can't recall seeing it very often (or at all) in nurseries.

Keep up the great work as this blog is a terrific resource.


Gaye from the Hunter said...

hi Peter,

your comment has prompted me to investigate the word "aril".....

aril = an expansion of the *funicle into a fleshy or membranous appendage, sometimes partially or wholly covering the surface of the seed, and often brightly coloured, as in some Sapindaceae.

funicle = the stalk of the ovule.

It seems ants have a considerable effect on both seed survival and germination.

On the hard black shiny seed coat can be found an oily fleshy outgrowth known as an aril. Ants love to eat this. They take the whole seed back to their nests. Back at the nest the ants eat only the aril. So when ants collect the fallen seeds they are actually dispersing them safely. Safe from seed eating birds and mammals, tucked away in the sub soil, perhaps to lie there and wait until the next bushfire, when that hard seed coat will be cracked open, ready to receive the rain and grow into a new generation of Wattles.

So many questions. Thank you Peter for that little snippet of information that encouraged me to dig a bit deeper.