Lepidozamia peroffskyana

From Pacsoa
Revision as of 09:44, 1 November 2013 by Mike Gray (Talk | contribs)

Jump to: navigation, search
Welcome to the PACSOA Palms and Cycads wiki !

If you have any information about this plant, please help by updating this article. Once you are registered you can contribute, change, or correct the text, and even add photos on this page. Click on the edit tab above and play around. Any mistake can be easily corrected, so don't be afraid.

Figure 1. Multi-trunked plant.

Contents

History:

Lepidozamia peroffskyana, described in 1857, was named after Count Peroffsky, a Russian nobleman and benefactor of the St Petersburg Botanic Garden, where the type plant was cultivated.

Distribution Range:

L. peroffskyana is a large cycad that is endemic to Eastern Australia and which grows on the north coast of New South Wales and in south-eastern Queensland. It has a distribution range that stretches over approximately 700 kms of coastal and near coastal areas and which extends from near Taree on the mid-north coast of New South Wales to near Gympie, north of Brisbane, in Queensland.

Habitat Conditions:

L. peroffskyana is the tallest growing cycad in New South Wales. It normally grows in large dense stands - often in abundance, with adult plants growing so prolifically that the fronds of numerous plants actually overlap each other. It grows in abundance at altitudes of up to 700 metres near Dorrigo, which is the wettest town in New South Wales, with an annual average rainfall of approximately 2,000 mms (80 inches). Forest areas near Dorrigo are heavily infested with leeches, ticks and mosquitos.

L. peroffskyana generally grows under a eucalypt canopy in habitat conditions ranging from stabilised sand dunes and sand hills near the ocean to steep slopes on mountain ranges adjoining the sometimes narrow coastal belt. On the mountain ranges it grows in areas of wet sclerophyll forest bordering on rain forest, while closer to the ocean it can be found growing in depauperate littoral rainforest or open scrubby forest.


Climatic Data:

Climatic data relating to Murwillumbah, Coffs Harbour and Taree, which are situated at the northern extremity, centre and southern extremity of the New South Wales distribution range of this cycad respectively (and covering altitude, annual average rainfall, number of annual rain days and frost days and minimum and maximum temperatures reached at least once per week in July and January respectively) is as follows: AnnualAverageRainfall (mm) Rain Days Frost Days JulyMinimum °C JanuaryMaximum °C

Rainfall Patterns:

Over 60% of the annual rainfall covering the New South Wales distribution range of L. peroffskyana falls in summer and autumn, but overall the rainfall pattern is split on a seasonal basis, with 50% of the annual rainfall falling in spring and summer and 50% in autumn and winter. The seasonal rainfall pattern is as follows: Summer - 32%, Autumn - 32%, Winter - 18% and Spring - 18%.

Figure 2. Plants in habitat.

Principal Characteristics:

The principal characteristics of L. peroffskyana are: (1) a tall columnar trunk, normally standing 0.6 to 1.8 metres above ground level to a maximum height of approximately 5 metres - and ranging up to 35 cms in diameter, (2) a maximum of approximately 50 to 60 very glossy, dark green fronds that range up to 2 to 3 metres in length, (3) an untwisted rhachis, (4) entire pinnae, rising in an arching manner from the rhachis, then tending to droop, and (5) seeds with reddish coloured flesh, though occasionally with yellow coloured flesh.

Figure 3. Branched plant, estimated height 5 metres.

Trunks:

This cycad normally has an unbranched trunk, though in some stands it is not uncommon to find multi-headed plants or plants with branched trunks, with some plants having as many as 5 separate trunks (Figures 1&3). This tendency for plants to branch occurs frequently in some stands, but in other disjunct stands it is rare to find plants with branched trunks. The tallest L. peroffskyana plant that I have seen growing in New South Wales (Figure 3) was a plant that branched approximately 1.8 metres above ground level into 2 separate trunks that were, respectively, an estimated 3.1 and 3.3 metres in length thus attaining a maximum height of a little over 5 metres. The trunks and crowns of L. peroffskyana are often host to epiphytic plants such as Platycerium bifurcatum (elkhorn), Asplenium australasicum (bird's-nest fern) and Davallia sp. (hare's-foot ferns).

Fronds:

New fronds of L. peroffskyana are produced in flushes and rise almost vertically with furled pinnae for a considerable portion of their ultimate length (Figure 4) before the pinnae begin to unfurl. The pinnae on new fronds are a distinctive bronze (sometimes brownish) colour, but change to a glossy dark green as the fronds reach full size and undergo a hardening process. With age, the fronds tend to arch and produce a graceful palm-like appearance. During the relatively short period of time in which new fronds reach full size and harden up, the pinnae are extremely glossy and shiny so much so that, when new growth is uniformly produced in a stand after a bushfire, the new fronds brilliantly reflect the sunshine, when the sun is directly overhead (Figure 5).

Pinnae:

The pinnae rise alternately from the midline of the rhachis, as opposed to the pinnae on various Macrozamia species which rise or extend laterally, from the edges of the rhachis. In contrast with most Macrozamia species, the pinnae on L. peroffskyana do not have a pronounced (or sometimes coloured) callous at the point where they join the rhachis, nor do they have sharply pointed tips like Macrozamia communis and M. johnsonii (which adds greatly to their attraction as either a potted plant or a garden specimen).

Figure 4. Plant with newly emerging fronds.
Figure 5. The sun reflected from new growth after a bushfire.

Cones:

Both male and female cones are large and unlike Macrozamia cones do not have a peduncle. Female cones are usually solitary, though plants with 2 cones are not uncommon (Figure 6). Female cones are also the largest cones on any New South Wales cycad, measuring up to 50-60 cms in length and 20-25 cms in width when mature. Additionally, the sporophylls on female cones of L. peroffskyana do not have elongated spine-like appendages like those on Macrozamias. Like female plants, male plants usually have solitary cones, though plants with 2 cones are not uncommon.

Figure 6. Two female plants, each with two cones.
Figure 7. Distended male cone.

Male cones open up in an unusual spiral fashion and distend when about to shed pollen (Figure 7). Prior to distending, male cones measure up to 50-60 cms in length and 10-12 cms in width, but when fully distended can extend to 1 metre in length. After distending, the sporophylls on the male cones become a breeding chamber for Tranes sp weevils, which are ultimately responsible for fertilisation of the female cones. The activities of these weevils which are attracted in swarm proportions to the male cones (Figure 12) at about the time they are ready to open up, result in the rapid destruction of the cone (as the sporophylls are consumed by larvae). A Tranes species weevil, Tranes "lyterioides" is also associated with the pollination of Macrozamia communis (Figure 13).

Seeds:

Seeds of L. peroffskyana are the largest of any New South Wales cycad and measure up to 6 cms long and 3 cms in diameter. Seeds are normally red coloured (Figure 8), but occasionally yellow coloured seeds are produced (Figure 9).

Figure 8. Female cone with red seeds.
Figure 9. Female cone with yellow seeds.

A unique feature of L. peroffskyana is its rare capacity to produce sporophylls holding either 1 or 3 seeds, as opposed to Macrozamias which only produce 2 seeds per sporophyll. These 3-seed sporophylls (Figure 10), which are only found in the basal area of a cone, have 2 seeds positioned normally, with the third seed situated above and in the middle of the other 2 seeds, so as to form a triangular pattern. Sporophylls with 1 seed (Figure 10), which are only found in apical section of a cone, are also an unusual feature of this species. The flesh on the seeds of this species tends to be eaten by kangaroos (which normally drop the seeds in close proximity to the parent plant, where they often germinate in large numbers) and possums (which normally drop the seeds under a nearby tree). Rats also eat the kernels after gnawing through the shell, often leaving quantities of half-shells in a cache under a log.

Figure 10. 1-seed and 3-seed sporophylls.

Regeneration:

Natural regeneration of L. peroffskyana in the wild is prolific as evidenced by the large number of seedling plants that are evident in the immediate vicinity of female plants, though very few of these seedlings ultimately grow to maturity (Figure 11).

Figure 11. Seedlings growing near a parent plant.

Pollination:

A recent study into the pollination of female L. peroffskyana cones, by John Hall, in the form of a thesis which comprised an integral part of his Batchelor of Science (Honours) degree (Department of Botany, University of Queensland), has proven beyond doubt, as a result of observations and experiments, that L. peroffskyana is pollinated exclusively by host specific Tranes sp. weevils, which breed in the male cones and "which visit the female cones in large numbers." In his thesis "Reproductive Ecology of the Australian Cycad Lepidozamia peroffskyana: A Host-Specific Pollination Between a Cycad and a Weevil", John stated that: "The cycad Lepidozamia peroffskyana is pollinated exclusively by the host specific Tranes weevils which carry out their life cycle within the tissues of the male cone and which visit female cones in large numbers. The results of the pollinator exclusion experiment (......) clearly indicate that when Tranes weevils are excluded from L. peroffskyana female cones, the pollination of ovules is essentially reduced to zero. Although several insects exploit L. peroffskyana as a host plant (......) only Tranes weevils are associated with both male and female cones, and hence they represent the only possible candidate for the insect pollination vector."

Figure 12. Tranes sp. weevils congregating on a male cone.

John also found that: (1) Tranes weevils congregated in spectacular numbers on male cones of L. peroffskyana some 24 hours before the cones commence to distend; and that one male cone collected for dissection was found to contain more than 700 weevils, (2) that airborne pollen was not consistently recorded beyond a 2 metre radius surrounding the pollen shedding male cones, (3) that the pollination of L. peroffskyana cones was effectively zero when Tranes weevils were successfully excluded from gaining access to female cones, (4) that the results of his study: "unequivocally demonstrated that wind plays no role whatsoever in the pollination of L. peroffskyana."

Figure 13. Tranes "lyterioides" weevil ex Clyde Mountain.

Idiosyncrasies:

As mentioned previously there is a tendency for these plants to branch in some habitat locations, but rarely in others. It is also noticeable that the average size of plants varies in different habitat locations for example, plants at Mt Tamborine (in south-eastern Queensland) are generally taller and more robust than plants at Dorrigo (which is located some 250 kms south of Mt Tambourine), even though in both locations the plants grow on steep slopes of mountain ranges that are reasonably close to the ocean. Additionally, plants growing on generally flatter areas near Taree are significantly smaller than those growing at Dorrigo. In the Byron Bay area, somewhat unusually for a cycad, L. peroffskyana grows alongside the Australian native palm, Archontophoenix cunninghamiana (the "bangalow" palm).

Effect of Fire:

L. peroffskyana has adapted to bushfires in the same manner as many other Australian native species. It is often found in State Forests that are subject to programmed cyclic hazard-reduction burn-offs (under the control of experienced Forestry officers). In the aftermath of a bushfire, cones are sometimes produced prior to the emergence of new fronds. Note photo (Figure 14) which shows a male plant with no fronds, but with a distending cone. A female plant can be seen in the background with a mature cone, but also with some newly emerging fronds.

Figure 14. Male and female cones emerging after a bushfire.
Figure 15. Female cones emerging after a bushfire.

Propagation:

Propagation is solely from seed, as this species does not normally produce offsets (suckers) though it is conceivable that a single 'head' removed from the occasional plant, that has produced multiple 'heads' as a consequence of being damaged, may be able to be successfully propagated in the same manner as a sucker or an offset from a Cycas revoluta plant.

Conservation:

From a conservation point-of-view, this species can be found growing in large dense stands in a number of State Forests, National Parks and vacant Crown Land and is not considered to be at risk.

Cultivation:

This species, which is probably the most widely cultivated New South Wales cycad, requires no special treatment, in either the garden or a container, to produce an extremely attractive and graceful specimen. It is fast growing and will flourish in well drained soil, preferably (but not essentially) in filtered sun, with moderate applications of fertiliser and reduced watering during winter months. Pest problems are similar to those encountered with other cycads. Scale is not uncommon in plants in cultivation (particularly indoor plants), but is treatable with applications of White Oil.

Trunk Boring Weevils:

Trunk boring weevils, such as Melotranes internatus (Figure 17) and Demyrsus meleoides (Figure 16), that are inadvertently introduced into a home garden environment, can cause massive collateral destruction to seedlings and mature plants in either pots or in the ground. These weevils are often found in 'sick' or damaged L. peroffskyana plants in the wild; and sometimes in healthy plants in habitat locations though they do not appear to cause any permanent damage to such healthy plants. Unhealthy plants appear to be used as breeding chambers and the resulting larvae feed on plant tissue, making small tunnels as they proceed, culminating in a honeycomb-type pattern of tunnels that cause surrounding areas of the caudex to begin to rot with the ultimate effect on the plant being terminal. In a home garden environment, the first obvious sign of weevil predation normally occurs when an apparently healthy plant suddenly collapses at ground level, because the caudex has totally rotted.

Figure 16. Demyrsus meleoides weevil specimen.

The damage that can be caused to cycads by Melotranes internatus (previously Tranes internatus) was the subject of an article on "Cycad-Insect Relationships" which I contributed to Issue No 34 of "Palms & Cycads." In this article mention was made of a report that appeared in Volume 3, Issue No 2 of the Cycad Newsletter in February 1982, concerning the arrival of a weevil (then) identified as Tranes internatus into the U.S. in the late 1960's and 1970's in the caudices of Australian Macrozamias and to significant problems that subsequently occurred in Los Angeles. The above report indicated that these weevils were unaffected by their host caudex being subjected to methyl bromide fumigation. Obviously the methyl bromide had not penetrated deep enough in the caudices to affect the weevils. Further historical evidence of the activities of Melotranes internatus is available by reference to an article written, over 120 years ago, in 1886, by J. O. Westwood in a Belgian Entomology Journal. In his article, Westwood described the ravages caused by larvae (then) identified as Tranes internatus which had been found in the caudex of an imported Australian cycad in the city of Ghent. The relevant plant which was described as "Zamia corallipes" was probably either M. spiralis or M. communis, though there is insufficient evidence in the article to now positively identify the particular Macrozamia species involved. Melotranes internatus was thus capable of surviving a lengthy surface voyage to Europe in the 1880's and, also, withstanding methyl bromide fumigation treatment after caudices were imported into the U.S.A and, in both situations, was able to reproduce in a new and different environment.

Figure 17. Melotranes internatus weevil and larva.

Three conclusions about Melotranes internatus can be drawn from the above: (1) that adult weevils live deep inside cycad caudices, possibly in tunnels created by larvae, and can resist most normal insecticide/fumigation treatments, (2) that when removed from their own environment, the weevils are isolated from their natural enemies (if any) and are able to freely multiply, and (3) that there may be an extremely long interval of time between the arrival of Melotranes internatus in a home garden and its emergence as an identifiable problem. Care should be taken to prevent these weevils from being introduced into a home garden environment by avoiding purchasing (or otherwise acquiring) plants that are suspected of having been taken from the wild. In addition, a careful examination of nursery-bought plants should also be undertaken before they are introduced into a home garden environment. Having seen evidence of Melotranes internatus on L. peroffskyana plants, it is my opinion that the purchase of L. peroffskyana plants taken from the wild (or the taking of any cycads from the wild) is somewhat like a lottery, with the chance that if you happen to end up with a plant that is infested with Melotranes internatus, you may unknowingly have a mini-ecological 'time bomb' on your hands.

Affinities:

L. peroffskyana is closely related to (but much smaller than) L. hopei, the only other member of the genus. The much broader and marginally darker fronds of L. hopei render the two species easily identifiable? (Note: This article is a further revised version of two previous articles that I have written about Lepidozamia peroffskyana. The first article was printed in Vol No. 38 of Palms & Cycads in January 1993; and a revised article was printed in Vol No. 107 of Principes minor in July 2002).

Acknowledgements:

I would like to thank Rolf Oberprieler, from CSIRO Entomology, for his expert advice about weevils and, also, for allowing me to reproduce photographs of various weevils. I would like to congratulate John Hall for his pioneering studies relating to the pollination of L. peroffskyana; and, also, to thank him for providing me with copies of both his theses. I would also like to thank Craig Thompson for freely sharing his vast botanical knowledge with me. Over a long period of time, Craig and I have visited habitat locations for most New South Wales cycads. Craig and I have also been privileged to escort a number of overseas visitors to various cycad habitat locations in New South Wales, including: Cynthia and Ted Giddy (1984); Loran Whitelock (1985); Cynthia Giddy with Elsa and Piet Vorster (1990); and Piet Vorster with Wynand van Eeden (2006). Finally, I would particularly like to thank my wife, Margaret, and Craig's wife, Nurelle, for their understanding and support as Craig and I ventured off infrequently (or too frequently, perhaps!) into the back of beyond, looking for cycads.

References:

Relationships between Cycads and Insects: Their Ecological and Evolutionary Significance. Reproductive Ecology of the Australian Cycad Lepidozamia peroffskyana: A Host-Specific Pollination Symbiosis Between a Cycad and a Weevil.

Contributed by:

Paul Kennedy (Text)
Craig Thompson and Paul Kennedy (Figures 1-15)
Rolf Oberprieler (Figures 16&17)

External Links:

Cycad Pages, IUCN, JSTOR, Trebrown

Google, Google Images, Flickr, PACSOA Forums