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Another burning question: hunter-gatherer exploitation of Macrozamia spp.

Abstract

Macrozamia seeds have long been considered an important economic resource to Australian hunter-gatherers. As a result of limited ecological data during the 1970's-1980's, seed production in Macrozamia spp. has been conceptualised as low yield and irregular, but easily stimulated through pyrogenic manipulation to produce high yield, regular resource gluts. This paper reviews and synthesises ecological data on Macrozamia ecology and seed production collated over the last few decades to argue that current archaeological conceptions of Macrozamia seed production and reproductive responses to fire are flawed, and to further consider how these resources were used in the past.

Keywords: Macrozamia, fire, seed production, Australia, hunter-gatherers

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Macrozamia is a genus of cycad found in many parts of Australia. The shells of these edible seeds have been found in archaeological sites in the Central Queensland Highlands (Beaton 1977, 1982, 1991a, 1991b; Mulvaney and Joyce 1965), New South Wales (Beck 1989, 2006; Lampert and Steele 1993; McCarthy 1964; McDonald 1992; Pearson 1981; Tindale 1961) and Western Australia (Smith 1982, 1996). This resource has attributes which make it particularly interesting from both forager and archaeological perspectives. It is in many ways a classic lower-ranked resource; the plants are generally unreliable producers of kernels, and the kernels are highly toxic unless leached, roasted or aged (Beaton 1982: 55-56; see also Beck 1992 for Cycas spp.). At the same time, seed cones are highly visible on plants while they develop and mature, the seeds can survive for extended periods on the ground, and they have the potential to be stored (Beck 1992: 141).

Based on analogy with the ethnographically recorded use of Cycas species in the Northern Territory and the limited ecological data available at the time, Beaton (1982) argued that large Macrozamia moorei assemblages discovered in the Central Queensland Highlands with estimated densities of 400-600 seeds per [m.sup.3] (Beaton 1977: 72; Beaton 1991a: 12, 1991b: 81, see also Asmussen 2008) were best explained as the result of intensive exploitation to support large gatherings. This was possible, he argued, because Macrozamia seed production could be artificially synchronised through the use of fire. This view was supported by an observation of a seven-fold increase in the production of edible female seeds following a 'small but intense' fire in a population of Macrozamia communis in New South Wales (Beaton 1982: 52-53). This led a number of archaeologists to argue that this was an example of a substantial economic and social intensification in the midto-late Holocene (e.g. Gamble 1986; Lourandos 1997). If correct, this was evidence of a direct and active manipulation of plant resources on a large scale, with an antiquity of 4300 years (Beaton 1982).

This model was formed during a period in which relatively little was known concerning Macrozamia. Since the 1970's a great deal of data has been amassed by ecologists on the ecology, life history and reproduction of different species in this genus. While this ecological research is not aimed at addressing archaeological questions it provides the data needed to develop an understanding of the determinants of seed production, a more complete account of the limits and possibilities of Macrozamia as a forager resource, and to assess the feasibility of the kind of pyrogenic manipulation envisaged by Beaton. The first part of this paper presents an overview of Macrozamia and the factors influencing seed production. The second section reviews studies of the effect of fire on Macrozamia to determine if hunter-gatherers could use fire to reliably induce mast seeding events. The third section collates data from multiple ecological studies to provide a quantitative analysis of seed production and variability of seed production in four species, and discusses broad implications for hunter-gatherer use.

Background: Macrozamia ecology and seed production

Macrozamia is one of the four genera of cycads present in Australia: Bowenia, Cycas, Lepidozamia and Macrozamia (Jones 1998:14). Macrozamia are endemic to Australia, and its ca, 41 species (Forster 2004:85) grow in open forests and woodlands in subtropical and temperate regions, from the coast to inland gorges in Queensland, New South Wales, Western Australia and the central desert (Jones 1998:232). While they share many attributes with the better known Cycas spp. found in the Tropical North, Macrozamia spp. are adapted to a variety of cooler or drier environments with less reliable rainfall. Cycas spp. prefer warm moist habitats where rainfall is distributed over most of the year, while Macrozamia spp. are often found in dry (xeric) habitats of low, seasonal rainfall (Jones 1998:16).

Although slow growing, these palm-like plants can live for many decades or centuries (Jones 1998:15). One study of 20 large Macrozamia riedlei plants (1.5-3.0 m in height) suggested their ages ranged between 670 and 1530 years (Pate 1993:126). Female Macrozamia plants produce large ovules in a cone (megastrobilis), while male plants produce pollen in a cone (microstrobilis) (Jones 1998:15). Reproduction in Macrozamia occurs only from seed, and species vary in the time taken to reach reproductive maturity (Jones 1998:56). It is common for plants to occur as small colonies or as scattered individuals which are often separated by considerable distances (Jones 1998:57). There can be substantial inter-population variation in the age and sex structure of populations, the numbers of mature reproductive plants, and the density of plants in populations.

Macrozamia plants mast seed. Mast seeding is defined as the 'synchronous production of seeds within a plant population within one year' (Ballardie and Whelan 1986:101). In a mast year, 70% of all plants in a population may produce strobili, while as few as 2% of plants may produce seed in non-mast years (Ballardie and Whelan 1986:100). The spatial extent of masting is variable. While small groups of plants within a several hectare area may mast, plants in surrounding areas may not produce seeds (Ballardie and Whelan 1986:101; Kennedy et al. 2001:16). Mast seeding is relatively infrequent, occurring at 'unpredictable intervals' (Terry et al. 2008:321) and is usually followed by several years of 'dormancy' in which few seeds are set (Ballardie and Whelan 1986:101; Kennedy et al. 2001:16).

There are inter-species differences in the number of seeds produced per strobilus in large mature plants. For example, M. moorei plants can produce over 300 seeds per cone (Beaton 1982: Table 1) with kernels (ovules) weighing 18 g; Macrozamia communis plants can produce strobili weighing 5 kg, containing 150 seeds per cone (Kennedy et al. 2001:15; Ornduff 1990:96), with kernels weighing approximately 8 grams; while M. riedlei cones can weigh 14 kg and contain 50-80 seeds per cone (Ornduff 1985:395), with kernels weighing 8 g. The number of cones per female plant can vary between one and four (Jones 1998).

Cones are visible on plants for many months while they develop and mature; for example cones are visible on M. communis for approximately 10 months. The visibility of strobili developing on plants would allow hunter-gatherers to anticipate the size and location of the next harvest. Following seedfall, seeds have long after-ripening periods of six to 12 months and a germination period of 12-18 months (Jones 1998:232). Large quantities of seeds can remain beneath plants for extended periods of time. For example, Ballardie and Whelan (1986:102, Figure 1) observed that between 50-75% of the seeds produced by M. communis remained within one metre of female plants during a five week observation period. Ornduff also observed seeds beneath plants throughout the range of M. communis (Ornduff 1990:97). A more recent experiment by Snow and Walter (2007:593, Figure 2) found that 87% of M. lucida seed remained within four metres of parent plants after 120 days, after which the experiment was terminated. The limited dispersal of seeds would have allowed foragers to leave seed beneath plants and collect it in the future, or consume aged seeds while foraging (Beck 1992; Beck et al. 1988).

While Macrozamia seeds can represent quite a significant food resource, it is now clear that there are definite constraints on production by individual plants. The production of seeds by female plants represents a considerable investment of energy (Jones 1998:44). Plants accumulate large reserves of water, starch and nutrients in their stems and root tubers (Pate and Dixon 1982; Whitelock 2002:6). These reserves are built up over several years, and are depleted during cone production by female plants (Jones 1998:48, 64; Ornduff 1985:395-6; Pate 1993:126; Pate and Dixon 1982). Cone production by female plants is significantly more energy demanding in comparison to males (Newell 1983; Ornduff 1985:396). While detailed research on Macrozamia has not been conducted, one quantitative study of Zamia pumila indicated that female plants used 7.6 times more energy per reproductive event than male plants (Tang 1990:370). As a result, there is often an interval between reproductive episodes of three to four years when female Macrozamia plants appear to rest, during which depleted reserves are recouped by the plant (Jones 1998:44, 65; Pate 1993:127). While this has not been studied in Macrozamia, in a study of female Cycas revoluta more than a year was required to synthesize the amount of starch used in seed production (Theiret 1956:12). Alternating periods of growth and prolonged rest can occur, and gaps of 10-15 years between coning events have been observed in some species (Jones 1998:15).

Local environmental conditions, including water availability and soil nutrients, can have a substantial impact on plant growth and the frequency of seed production in mature plants (Connell and Ladd 1993:94; Jones 1998:72). Water is crucial to plant growth and survival (Whitelock 2002:27). Studies indicate that plants in high rainfall regions produce more female plants, and that these grow and mature more quickly, produce more cones per plant, and reproduce more frequently than plants in less advantageous positions. For example, increased seed production has been observed in M. riedlei plants growing in municipally maintained gardens in Western Australia, where the female plants commonly produced five cones each, while three M. riedlei populations with 33% or more female plants occurred in areas of relatively high rainfall, and a fourth occurred in a habitat in which competition was reduced and artificial watering was conducted throughout the summer (Ornduff 1985:393, 396). Baird also noted female M. riedlei plants receiving water throughout the summer produced large cones every alternate year (1939:156, 1977:3, 11). Rainfall also increases the uptake of nitrogen, an important plant nutrient (Halliday and Pate 1976:352). Availability of nutrients may also be an important factor. M. riedlei plants growing in lateritic soils were smaller and produced fewer cones than those growing in rich soils of the coastal sand plains (Baird 1939:154). Ornduff also suggested coning frequency was reduced in populations situated in heavily shaded environments (1991:10). Drought may also affect coning cycles in some species, as stored water and nutrients in plant stems are utilised to survive drought, rather than produce seeds (Queensland Herbarium 2007:22; Whitelock 2002:27, 275).

Macrozamia and fire

Fire is an unavoidable feature of most environments in which Macrozamia grow, and can have both positive and negative effects on plants and populations. The coralloid roots in Macrozamia plants contain cyanobacteria, which fix atmospheric nitrogen, making it available as a nutrient to the plant (Grove et al. 1980:277; Halliday and Pate 1976:356; Whitelock 2002: 17). This is important for plants growing in impoverished soils (Jones 1998:63). Studies in M. riedlei have indicated that nitrogen mineralisation is greater in burnt populations, and increased levels can persist for several years following fire (Grove et al. 1980). Infrequent, low-intensity fires may produce other beneficial effects, including opening canopies, increasing in light levels, and reducing competition in the first few years following a fire (Grove et al. 1980:279; Ornduff 1990:97), which can lead to increased plant growth and cone production.

Adult plants are usually resistant to all but the most intense fires, due to the presence of old leaf bases on the trunks of plants which insulate live tissue (Jones 1998:65; Queensland Herbarium 2007:20). However, relatively frequent or hot fires may have a negative influence on plant growth, fecundity and longevity (Preece et al. 2007:605). Intense fires can kill seeds on the ground before they can germinate, kill seedlings and juvenile plants, and kill adult plants growing in moderately well watered (mesic) environments (Terry et al. 2008:321; Queensland Herbarium 2007:20-21), kill insect pollinators, and can increase the susceptibility of plants to pests and diseases (Terry et al. 2008:321). Thus, fires can produce long-term effects on population size and structure. While it is beneficial for plants to produce new sets of leaves following fire (Pate 1993:127), if fire regularity is high, the plant may direct energy reserves to replenish leaves, rather than the production of seed (Ornduff 1990:97).

Many ecologists have argued that fire plays a role in triggering masting events in at least some species (Jones 1998:65), although the exact mechanism stimulating masting and the role of fire is still a matter of some debate (Binns and Meek 2008:378; Jones 1998:65; Preece et al. 2007:602). In this view, masting often occurs two to three years following fire in the habitat (Baird 1977:11; Burbidge and Whelan 1982:63; Terry et al. 2008:322, 324). Baird observed that in M. riedlei, 'cones are found, in plants old enough to reproduce, in the second year after a fire' (1977:11) but did not present quantitative data. In a later study, Pate suggested that coning was 'strongly stimulated by fire' (1993:125) in two populations of M. riedlei plants: 'prolific coning' (1993:126) occurred in a sampled population of 92 plants at Badingarra, and 47% of the female plants at Dwellingup produced seed in the second season following fire (1993:127). While these cases are frequently cited in support of the argument, there are limited quantitative data concerning seed production resulting from masting events and no longitudinal studies to confirm a direct effect.

It is worth noting that other environmental factors may have influenced cone production in these cases. Baird had observed that the region had been subjected to an intense wildfire after prolonged drought, followed by 'two above-average rainfall winters' (1977:3, 11). Pate also noted several factors which may have affected the marked post-fire response in the M. riedlei populations: fire-free intervals of eight years and over 10 years prior to the observed masting event, during which no seeds had been produced, the Badgingarra/Watheroo population was comprised of exceptionally large plants of some antiquity with large above ground trunks in which starch could be stored (1993:126-7).

The intensive exploitation argued by Beaton depends on fire acting as a reliable trigger of mast seeding. However, current data indicate that populations do not automatically respond to fire by masting. Terry et al. (2008:326) found three of 11 M. platyrachis populations did not mast following fire. It also appears that masting can occur without fire. Ornduff (1990:97) studied populations of M. communis and found that the females in one population, which was not fired, produced 'enormous' quantities of seed in a masting event, but another population, which had been burnt, did not produce any seed. While studying seed predation in New South Wales M. communis populations in the 1980's, Ballardie observed two masting populations, one which had not been burnt for four years, and another which had not been burnt for seven years (1984:24). These examples indicate there is variability in the responses of plants to fire, and the temporal length between the fire and the production of seeds.

There is also evidence that frequent fires can suppress seed production. Ornduff (1990:97) suggested that cone production in one M. communis population was suppressed as a result of the two to three year frequency of controlled burning. However he also noted that cone production was sporadic, even in the absence of regular burning (see also Kennedy et al. 2001:16). Ornduff commented that 'the periodicity with which fire is used as a fire suppression method may affect the frequency of cone production in some populations, perhaps preventing it entirely' (1990:92). Pate studied seed production in two frequently burnt M. riedlei populations in Western Australia: Yanchep, burnt every three years over a 12 year period, and a second population at Dwellingup, which was burnt three times over a period of 14 years. The Yanchep population showed a coning ratio of males to females of 12:1, while the Dwellingup population showed a coning ratio of 9:1 suggesting that fire was suppressing coning in female plants but not male plants (Pate 1993:127). This led Pate to suggest that frequently burnt female M. riedlei plants displayed a protective mechanism 'negating the strongly pyrogenic effect of fire on reproduction' to prevent the 'over-exhaustion of plant resources through closely repeated episodes of coning' (1993:127). Ornduff also suggested 'that fire may result in lowered cone production should not be ruled out' (1985:397) for some populations of M. riedlei.

What are the implications for Beaton's argument? The evidence suggests the effect of fire would be unpredictable without a very high level of environmental monitoring and knowledge of the factors affecting seed production. Any fire-induced seeding would be restricted to those plants with adequate stored energy reserves. Some factors, such as extended drought, may act to synchronise energy reserves over large areas. However, different populations will have different rates of acquiring energy based on access to water, sunlight and soil nutrients, producing different seeding patterns (e.g. Birdwood Parade, Table 2, below), and these variations would tend to put energy reserves and seed production out of synch. This innate unpredictability would be partly mitigated by the fact that seed becomes visible on the plants many months before it is ready for consumption, allowing planned exploitation of the seed.

This does not mean the foragers did not use fire as part of a broader management strategy to preserve plants or increase overall seed production. The available evidence suggests that regular low intensity fires could be used to reduce the risk of damaging intense fires. In an effort to preserve vulnerable and endangered plant populations, ecologists have suggested populations of Macrozamia plants could be burnt in a mosaic pattern (Terry et al. 2008:330). Current recommendations suggest fires should be avoided when plants are coning and receptive to pollinators, between October and March (Terry et al. 2008:321; Queensland Herbarium 2007:21). A fire-free interval of five years has been recommended for specific populations (Borsboom 2006; Terry et al. 2008:330).

Quantifying Maerozamia seed production

To assess how hunter-gatherers might have used such a variable resource, specific quantitative data on the variability of seed production is required. Since the 1970's, ecologists have identified substantial inter-species variation in the age and sex structure of populations, the numbers of mature reproductive plants, and the density of plants in populations. These data have been reworked here to provide baseline information on inter-annual variation in seed production within and between species, which can be used to develop more sophisticated models of resource availability and implications for the use of these seeds by foragers.

Seed production by species through time

A measure of Macrozamia seed production through time was obtained by collating data from information published in journals and government reports. Data were not available regarding the exact numbers of mature (reproductive) males and female plants in most of the populations. Ecologists can determine plant maturity using the number and size of leaves on plants; however the sex of the plant can only be determined by the presence of male or female cones on plants (Ornduff 1991:6-7). To be included in this analysis, studies had to present the number of female plants producing seed cones for each population at each observation event (usually years), and the total number of mature plants in the population. In some cases the data were presented in text as counts or percentages, while in others the information was derived from graphs. Data from Beaton's study (1982) were included in this analysis. Populations were counted as exposed to fire if authors made explicit reference to a fire having occurred in the study plots, as well as when the fire occurred. The timing of the fire in relation to seed production was inferred retrospectively by the researchers through field observations.

After reviewing the ecological literature, seven studies contained data which could be analysed to address the archaeological questions in this study. Seed production was able to be examined for 8233 plants from 47 populations of four Macrozamia species from three states: 15 populations of Macrozamia communis located between Kempsey and Batemans Bay in New South Wales (2221 plants, eight separate years of observations) (Beaton 1982; Ornduff 1990); 14 populations of Macrozamia lomandroides located near Bundaberg in Queensland (1323 plants, one year of observation; DEH 1998), Macrozamia parcifolia located near Maryborough in Queensland (N=953 plants, one year of observation; DEH 1998), and 12 populations of M. riedlei located in south-west Western Australia (N=3736 plants, 15 separate years of observations) (Baird 1939; Ornduff 1985, 1991; Pate 1993).

In this analysis, data were recorded by population and year of observation, creating 82 data points, each data point being the observed frequency of seed production for a given population for a given year. Given the limitations of the published data, seed production was calculated as the number of seeding females divided by the total number of mature plants identified in the population (male and female), expressed as a percentage.

Figure 1 presents a histogram of the percentage of mature plants that are coning females for the four Macrozamia species while Table 1 presents data on mean seed production by species. These data demonstrate that seed production is highly variable, and identify some interesting differences between the species. It is not possible to assess interannual variation in seed production by M. lomandroides or M. parcifolia, as seed production has only been observed for one year (1997). Only M. communis and M. riedlei have data spanning multiple years. A Kruskal-Wallis test indicated that there was a significant difference in the mean percentage of female plants producing seed between M. communis (N=28) and M. riedlei (N=34) ([chi square] = 4.019, df = 1, N = 62, p = .045). These data were also analysed for evidence of post-fire seed increase in M. riedlei and M. communis. The mean percent of mature plants which were coning females was higher for populations exposed to fire (see Table 1) for both species but Mann-Whitney U tests indicate that this was not a significant difference (M. riedlei U = 49.0, p = 0.53; M. communis U = 18.0, p = 0.47). In both cases the sample size is small and it is unclear if all fire events were identified. More data would be needed to adequately test the relationship between fire and Macrozamia seed production.

Variability of production within a population through time

Despite the great deal of published information concerning the general ecology of cycads, there have not been any comprehensive longitudinal studies undertaken concerning spatial and temporal variability in the frequency in seed production by individual Macrozamia plants or populations. Ornduff recorded population size and the number and sex of adult plants producing seed for specific populations in multiple years, providing 'snapshots' of seed availability in some populations at particular points of time (Table 2). Ornduff's data indicate that seed production can be variable between years within single populations, and between populations of the same species. The available data suggest that seed production can fluctuate significantly from year to year on a large scale. For example, Ornduff's data (Table 2) indicate that in 1983 five of six populations of M. riedlei produced seed, but in 1988 only one of six populations produced seed, and that population was artificially watered.

Ecological data also allow the consideration of the food value that could be provided by each plant. As Table 3 illustrates, Macrozamia plants can provide substantial amounts of seed, although this can vary between species. It is likely that populations of plants were far more extensive prior to European contact. Due to their toxicity, substantial numbers of plants (including M. communis, M. moorei and M. riedlei) were eradicated over the past 200 years to prevent stock losses (Adams 1925; Anon 1912; Bailey 1897; Seddon and Belschner 1930; Stewart 1899; Theiret 1956:26; Queensland Herbarium 2007:18). Today, some stands of M. communis are 'so immensely thick as to be almost impenetrable' (Kennedy et al. 2001:16). Where there were large densities of plants prior to European contact, it is feasible that Macrozamia was an important resource, with patterns of exploitation adapted to naturally occurring variation in seed production.

[FIGURE 1 OMITTED]

Discussion and conclusion

Macrozamia can be a resource of extremes, from little seed production to mast seeding events, with most production falling in the middle. There are few longitudinal studies, and little information on the scale of seed failure over large areas, however Ornduff's (1985, 1990b; Table 2 above) and Pate's data (1993) indicate that widespread failure of seed production can occur. Overall, the evidence suggests that foragers would need to adapt to the variability and unpredictability of seed production from year to year. This not only affects the amount of seed available for consumption, but it affects the amount of effort required to collect a given amount of seed from an area.

Different patterns of seed production may have affected the way people used the same resource throughout its geographic distribution. It is clear from the ecological data that seed production varies systematically between populations or 'groves' of plants within a region based on variations in water, nutrients, population structure and the maturity of plants. Large mature plants in relatively wellwatered areas, with open canopies and good soils will produce seed more reliably. Given that Macrozamia are long-lived plants with limited dispersal of seeds, identifiable populations with superior seed production would be visible and long-term features of the human landscape.

The past few decades of research on Macrozamia ecology have important implications for archaeological conceptions of its exploitation. Ecologists differ about the role of fire in triggering masting events. However, current data suggest seed production may not have been as easily pyrogenically manipulated as has been archaeologically modelled. Several factors including water availability, soil fertility and fire frequency and intensity, combined with population-level factors including the proportion of mature reproductive female plants, affect the frequency of coning and produce significant variations in seed production on a temporal and spatial scale. Given these interactions, the effects of fire on seed production may not have been easily determined or predictable prior to the setting of the fire. Until the results of longitudinal studies come to hand, we should be cautious in using Macrozamia as an example of surplus production to support inter-group social occasions (Lourandos 1997). Overall, it does not seem likely that fire could be used to synchronise seed production in the way envisaged by Beaton. Any large-scale intensive exploitation was most likely dependant on taking advantage of naturally occurring abundances.

While knowledge of the ecological characteristics of Macrozamia has been much advanced by several decades of research, there is still a great deal to learn. For example, longitudinal studies of seed production by individual plants across multiple populations over a wide geographic area, and across different species, analysed with other factors such as rainfall patterns, soil fertility, drought frequency and severity, fire frequency, intensity and season of burning are required. Although this research is likely to take several decades, these data may be used to further refine archaeological models of the use of Macrozamia as a resource, and the role of fire in seed production.

Acknowledgements

This paper was written with the support of a Wenner-Gren Richard Carley Hunt Postdoctoral Fellowship, and while I was a Visiting Fellow in the School of Archaeology, at the Australian National University. This research was conducted as part of a larger Doctoral research programme. Many thanks to Catherine Jordan at the Australian National Botanic Gardens Branch Library for her assistance in providing a copy of Pate (1993). I particularly thank Drs Irene Terry, Paul Forster, Paul Kennedy, John Hall, Ken Hill, Leonie Stanberg, Adrian Borsboom and John Atkinson for providing information and advice, and Paul McInnes, Peter Hiscock, Val Attenbrow, Pat Faulkner and anonymous reviewers for their insightful comments on a prior version of this paper.

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School of Social Science, University of Queensland, Brisbane Qld 4072, Australia. Email: brit.asmussen@exemail.com.au
Table 1. Mean seed production by species.

                            Percent of mature plants that
                            are coning females

                 N of
                 observed
Species          cases      Min       Max     SD

Macrozamia
  communis       28         0         47.7    14.0
Macrozamia
  lomandroides   14         0         11.4    3.6
Macrozamia
  parcifolia     6          0         3.8     1.7
Macrozamia
  riedlei        34         0         47.4    9.6

                            Percent of mature plants that
                            are coning females

                 N of
                 observed             Fire
Species          cases      Overall   mean    No Fire

Macrozamia
  communis       28         11.3      14.2    11.1
Macrozamia
  lomandroides   14         4.9       na      11.4
Macrozamia
  parcifolia     6          1.8       na      3.8
Macrozamia
  riedlei        34         5.3       14.9    4.0

Table 2. Percent of mature plants that are female plants
producing seeds. Data collated from Ornduff (1985: Table
1; 1990: Figure 2, Table 2; 1991: Table 1). Ornduff's term
"prior coning episode" refers to a sequence of cone
production culminating in seed maturation in early-mid
1986, and initiated in late 1984 (Ornduff 1990:93).
(^) Almost all plants large and mature; * plants artificially
watered and all mature, equal sex ratio; (+) shady
environment and dense underbrush.

                            Observation year, percent of
                            mature plants that are coning
                            females

Population
Macrozamia riedlei          1983                   1988
North Bannister             0                      0
Kings Park (^)              15.0                   0
Birdwood Parade *           21.7                   14.28
Pemberton (+)               3.0                    0
Whittaker's Old Mill (+)    4.3                    0
Caves Road East (+)         10.6                   0
Average                     9.1                    2.38

Macrozamia communis         Prior coning episode   1987
Kempsey Road                1.92                   3.8
Bombah Point                24.5                   24.5
Kearsley                    1.1                    8.0
Kurnell Peninsula           0                      17.4
Seven Mile Beach            11.4                   47.7
Merry Beach                 39.1                   0
Benandarah                  9.3                    0
Mossy Point                 15.4                   0
Mughorn Gap                 0                      4.4
Average                     11.41                  11.75

Table 3. Comparisons of inter-species differences in seed production
and coning intervals. * Mean derived using a sample of 10 seeds.

                No. seeds    Mean no.    No. cones
                per female   seeds per   per female
Species         cone         cone        plant

Macrozamia      50-150       95          1-4
  communis
Macrozamia
  moorei        240-360      300         1-8
Macrozamia      50-160       105         1-3
  riedlei

                Mean *       Kernel
                kernel       weight
                weight       per cone
Species         grams        (grams)     References

Macrozamia      8            760         Ballardie and Whelan
  communis                                 1986; Jones 1998;
                                           Kennedy et al.
                                           2001; Ornduff 1990.
Macrozamia      18           5400        Beaton 1982; Jones 1998.
  moorei
Macrozamia      8            840         Baird 1939; Ornduff
  riedlei                                  1985, 1991; Pate and
                                           Dixon 1982.
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Author:Asmussen, Brit
Publication:Archaeology in Oceania
Geographic Code:8AUST
Date:Oct 1, 2009
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