Orchids are attractive and abound in variety. It is the variety that often provides the challenge of identification. As a novice it can be a bit overwhelming. In the eye of the beginner, the experienced orchid hunters appear to have no difficulty with identification. Over the years they have accumulated various clues that guide them toward accurate identification.
This series aims to document the clues that orchid hunters use.
Prasophyllum and Microtis Leaves
The first in the series relates to distinguishing between Microtis and Prasophyllum leaves. When in flower it is easy to see which is which but not so when only in leaf; and as they do not always produce flowers it is helpful to be able to separate them out at leaf stage.
Both leaves are green. Both are cylindrical. Both are hollow. Both resemble onion leaves.
The differences can be found in one or two areas. Microtis leaves are always green at the base whereas Prasophyllum leaves usually but not always will have a red or purplish coloured base. To help in identification, it is necessary to examine the base by moving the leaf litter aside to see where the plant emerges from the soil.
Prasophyllum species that could have a green base are P. laxum, P. occulatans, P. sp Jip Jip, P. elatum, P. sp Sandplain, P. pallidum (although this is short and usually in bud when noticed), P. spicatum, P validum. So further observations are necessary.
Another other area of difference is that the broken leaf of a Microtis yields a mucilaginous (thick sticky) sap; the Prasophyllum leaf does not.
Within the segregate genera used by many NOSSA members, there are two other genera with similar leaves. They are Microtidium and Hydrorchis. Again they are green, cylindrical, hollow but only hollow in the lower half. The top half is solid.
It should also be noted that Microtis can form dense colonies but Prasophyllum will never form more than loose colonies.
Finally, if upon gently feeling the base of these leaves it feels solid, that will indicate that there is a bud and it will most likely flower this season.
Think of deserts and the image is that of a bleak barren landscape with little to see but this is not so. The conditions are harsh but there is a myriad, though not an abundance, of hardy fauna and flora if one but looks closely.
But concerning orchids – No orchids have been found in true deserts….. They also appear to be absent from the arid mountains of the far north-west, or at least no-one has ever found orchids there.
Orchids need moisture and so they do not grow on unstable soils such as dry sand-hills, gibber plains or the many saline areas of the far north but on the desert fringes there are micro-climates where the moisture, humidity and soil structure is just right (to quote Goldilocks) for orchids. This micro-climate is created by [s]hrubland [which] is … [an] … important dryland orchid habitat. Besides providing shade and shelter for the orchids, shrubs like the many species of wattles, Acacia and hop-bush Dodonea drop fine leaves which help to hold the soil together and slowly break down into humus rich with nutrient and water storing capability. These shrublands usually form in soils too dry or shallow for trees. Orchids of course have no need for deep soils as they are shallow rooted.
Of the five desert botanical regions, the Eastern region contains the most number of species with over a dozen species.
Orchids of the Eastern Region – this region is from the east of the Flinders Ranges to the New South Wales border and includes the Olary Spur and Lake Frome.
Arachnorchis toxochila – Dry Land Spider Orchid or Bow Lip Spider Orchid.
Corunastylis tepperi – Mallee Midge Orchid
Diplodium robustum – Common green shell-orchid.
Hymenochilus pagophilus – Mountain Shell-orchid
Microtis eremaea – Desert onion orchid
Microtis frutetorum – Common woodland onion orchid.
Oligochaetochilus bisetus species complex, Rusty rufous-hoods
Oligochaetochilus sp. Blue-bush Plain – Blue Bush rufous-hood (O. bisetus complex)
The Gairdner-Torrens region includes, besides the salt lakes it is named after, the Gawler Ranges and the southern part of the Great Victoria Desert. Though not as many species as the Eastern region, it contains some different species including a Sun Orchid.
The final two regions Lake Eyre and North-Western contain the vast expanses of desert of the far north of South Australia. Definitely not a place to find orchids yet one specimen has been collected from each of these two regions.
Oligochaetochilus sp. Everard Range (L. Scott 173), Mimili Orchid (possibly O. woollsii complex) from North-Western Region.
Oligochaetochilus sp. Gammon Range (O excelusus complex) from the Lake Eyre region.
It is unusual to find orchids in the desert because they only grow when there have been good winter rains which isn’t very often. But nevertheless, here in South Australia we have over 20 possible species – an astonishingly high number for such a harsh area!
Bates R J ed, South Australia’s Native Orchids, 2011 Native Orchid Society of South Australia
Map adapted from Flora of South Australia, Fourth Edition, 1986
There is a lot of information on growing orchids so much so that it can become overwhelming. As a novice, I’ve put together my observations which can be summed up in three key points.
One – Find a Mentor
The best and first thing to do is to join a local orchid club, such as the Native Orchid Society of South Australia (NOSSA), and find a mentor within the group. There are many books but nothing substitutes for that personal interaction with an experienced grower who will know both the plant and the adaptions needed for the local conditions. At the monthly meetings, NOSSA has a Grower’s forum where various aspects of growing orchids are discussed and questions answered. It is well worth attending.
Two – Have an Equipment Kit
There are some things that are essential and it is good to have a basic kit to get started. Later, more equipment can be added as one’s skill develops in growing orchids. The necessary items would include:
Labels – these can be proper plant labels from a garden store or wooden lollipop sticks, so long as they are waterproof.
Pen – indelible ink pen or pencil (there are pencils that can write on plastic) as it is pointless having a labelled plant with the details washed off.
it may be necessary to use both current name and synonyms on the label eg Corybas/Corysanthes
Wettable Sulphur – necessary for guarding against diseases and is available from garden centres but Tomato Dust can be a good substitute although it is half the strength.
Good nursery hygiene techniques are important
Dilute bleach, tri-sodium phosphate (and possibly a small blow torch for metal tools)
a different sheet for each orchid when dividing will help prevent transference of any disease, etc (don’t forget handwashing)
Ties and Stakes
Sieve for recovering tubers
Sheoak or pine needles for putting on top of the pots to stop soil and fungi splashing up on the undersize of the leaves
Pots – do not need to be fancy but the pot size will depend upon the species
Diuris prefer deeper pots; Corysanthes prefer wider, shallower pots whilst Pterostylis doesn’t seem to mind either
Three – Work within the Plant’s Growing Condition
This will require time, research, experiment and going back to the experienced growers. Each one of us eventually needs to find what is the best setup for our individual location but some general guidelines would be:
Start with plants that are suitable for your current climatic conditions. Obviously putting a tropical Dendrobium bigibbum under the patio in temperate Adelaide is not going to be successful. For the terrestrials it is better to start with Pterostylis curta or a Microtis than a fungi dependent Arachnorchis tentaculata.
Research the plant you want to grow and then create the micro-climate necessary for the flourishing of the plant. This will entail separating the orchids, don’t put shade lovers such as Corysanthes with those requiring brighter light eg the Thelymitra genus.