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Figure 6.
M. communis
with divided trunk, with tall single trunked specimen in background.
|
Trunks: When a trunk is produced it normally reaches up to (and rarely exceeds) a height of 1.2 metres above ground level and measures up to 0.6 metres in diameter. This height range accords with an extensive 1939 study by Brough and Taylor into the life cycle of M. communis
(which was then known as
M. spiralis
) though we have sighted one
M. communis
plant with a trunk that stood 1.5 metres above ground level.
M. communis
does not sucker and normally only produces a single trunk, though we have seen two only plants with bifurcated trunks.
Fronds:
M. communis
can have up to 100+ fronds which can reach up to 2 metres in length and which, at first, stand more or less upright but then, with age, tend to spread in a graceful arching manner to produce a palm-like appearance though plants are often seen in suburban Sydney with the fronds tied in a tight bunch, presumably to facilitate lawn mowing and allow ease of movement around the plants (by avoiding the sharply-tipped pinnae).
Seeds: The flesh on M. communis
seeds is normally reddish coloured, though occasionally yellow seeds are produced: but in some dense stands on the central coast it can either be red or yellow or, sometimes, an (intermediate) orange colour.
Plants producing seeds with different coloured flesh can be found growing side by side in the above stands. Red coloured seeds predominate, with yellow seeds being reasonably plentiful but with orange seeds being less common.
|
Figure 7.
M. communis
disintegrating cone with red seeds.
|
Figure 8. M. communis
with 3 disintegrating cones in crown of female.
Figure 9.
M. communis
seeds at base of female plant (mostly with flesh removed by kangaroos).
Figure 10. M. communis
seeds and young seedlings at base of female plant.
Figure 11.
M. communis
disintegrating cone with yellow seeds.
|
Cones: In the dense stands on the south coast, multiple female cones are much more numerous than single cones and plants with 2-3 cones are normal, while plants with 4 or more cones are not uncommon. At maturity, female cones measure up to 40 cm long and 18 cm in diameter, weigh approximately 5 kg and contain approximately 150 seeds.
M. communis
seeds measure up to 3.5 cm in length and 2.2 cm in diameter.
The sporophylls on female cones are heavily spined, with an elongated spine measuring up to 7 cm long on those sporophylls which are located toward the apical section of the cones.
Male plants normally produce more cones than female plants and up to 10 male cones on a plant have been recorded, though the norm is in the 3 to 5 range. Male cones measure up to approximately 40 cm long and 12 cm in diameter and are also spined, with spines
measuring up to 5 cm on the apical section of the cones.
|
Figure 12.
M. communis
female cones in habitat.
|
Comment: In 1985, we took (the late) Cynthia Giddy, who was visiting Australia for the first time, to Batemans Bay to look at M. communis
. Cynthia was amazed at the prolific number of
M. communis
plants which were growing in the area, particularly in one stand which was situated on a flat area of stabilised sand very close to the sea shore.
Cynthia was also surprised at:
- the extent of the eucalypt canopy cover
- the natural regeneration which was taking place (there were numerous self-germinated seedlings growing around many female plants)
- the fact that the plants were growing on beach sand almost immediately adjacent to the ocean
- the fact that the plants were growing on vacant land a mere 25 metres from a public road.
Kangaroos and possums are fairly common over the entire distribution range of this species and are responsible for eating the flesh off seeds which they have taken from (or which have fallen from) disintegrating cones. In this regard, these marsupial animals are very efficient seed cleaners.
|
Figure 13. M. communis
male cone + pinnae reduced to spines at the base of a frond.
|
Figure 14.
M. communis
in habitat.
Affinities: In respect of New South Wales cycads,
M. communis
has a very close affinity with
M. montana
and a lesser relationship with the very much smaller
M. reducta
.
M. montana
and M. reducta
were both identified in 1998 as separate
and distinct species.
M. montana
was named by Ken Hill, while
M. reducta
was named
by Ken Hill and David Jones. Prior to 1998, M. montana
and M. reducta
were both considered to fall under the
M. communis
umbrella.
Confusion has occurred, in respect of the identification of M. communis
and M. spiralis
, despite the reclassification of the nomenclature of
Australian Zamiaceae by Dr L. A. S. Johnson in 1959, when
M. communis
was created to cover what was previously incorrectly known
in New South Wales as
M. spiralis
.
Compared with M. communis
, M. spiralis
is a small cycad that grows
in a pattern of scattered individual plants or, sometimes, small clumps of plants.
It normally has between 2 and 12 fronds, which stand up to 60 to 90 cm above ground level
and has absolutely no affinity with
M. communis
.
<<< Previous
| Contributed by:
Craig Thompson and Paul Kennedy (Text & Figures 1-15)
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(Note: This article is a revised version of a previous article written by Paul Kennedy that appeared in Vol 60 of Principes minor in January 1993 and in Vol 41 of Palms & Cycads in October-December 1993.
The article takes into account the 1998 revisions of the Macrozamia communis
complex (by Ken Hill and, separately, by Ken Hill and David Jones), which resulted in the segregation of and creation of two new species:
M. montana
and
M. reducta
|
Figure 15. Getting that shot.
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