What plant is that? Zamia

Macrozamia fraseri and Macrozamia riedlei are types of Cycad. The Cycadales Order is an ancient group of plants that have lived since the Permian era, more than 200 million years ago. [1] Australia’s Macrozamias could have been eaten by dinosaurs! I knew them as Dinosaur Plants when I was a kid.

Macrozamia fraseri in bushland

Macrozamias fix atmospheric nitrogen through a symbiotic relationship with cyanobacteria found in the roots. The plant receives nitrogen in exchange for the sugars produced from photosynthesis. [2] The cyanobacteria also make neurotoxins, which end up in the leaves, making them poisonous. [3]

young-ish Macrozamia riedlei growing in bushland at my work

The two species look similar but don’t co-occur. Macrozamia fraseri grows throughout Perth on the Swan Coastal Plain, south to Mandurah and as far north as Jurien Bay. Macrozamia riedlei grows in the jarrah forests of the Perth Hills and South West [4] and in some places on the coastal plain, including bushland where I work. M. riedlei has flatter rather than keeled leaves (shaped like a ship’s keel) and smaller cones than M. fraseri. [5]

zamia in bushland at Lake Gwelup

Reproduction dioecious (separate male and female plants) fertile September – October [5]

This male Macrozamia fraseri grows in bushland at Lake Gwelup and had three cones this spring

zamia with male flowers

Fruit poisonous red flesh (sarcotesta) covers woody seed

zamia fruit at Star Swamp

This female plant has three cones with a red fruit in each segment of the cone

developing fruit

Associated wildlife birds such as Ravens, Silvereyes and Emus (Dromaius novaehollandiae) and introduced rats eat the fruit. [5] I saw ants crawling over one of the chewed seeds (below), I assume feeding on the red sarcotesta. I took a photo, but now I can’t find it.

gnawed fruit showing the hard seed within

Many Macrozamia are pollinated by thrips or weevils, each species having a specific insect pollinator. [6] The plant uses pheromones and food rewards to attract and repel the insect between the male and female cone. [7] Macrozamia riedlei is thought to be wind pollinated in combination with a weevil. [8]

zamia fluff

Some plants grow “fluff,” I don’t know its purpose.

Growth habit extremely slow growing

young zamia growing in the shelter of a fallen log

Despite looking dead, this Macrozamia fraseri at Lake Gwelup (below) is growing well. Zamia plants hold onto dead branches. I cropped out the green branches to better show the seedlings sprouting among the leaf litter. Click to enlarge.

zamia seedlings in the leaf litter

Resprouts after fire

zamia regrowth after fire

The same plant 8 months earlier after a fire burnt through Star Swamp Bushland Reserve

zamia one week after bushfire

Cultivation Macrozamia riedlei at the nursery

seed of Macrozamia riedlei

seed collection of fallen fruit, many have been gnawed by animals

first root

First root

first leaves

First shoot and leaves

Florabase record Macrozamia fraseri http://florabase.com/browse/profile/18119

Macrozamia riedlei http://florabase.com/browse/profile/85

References

  1. Royal Botanic Gardens Sydney (2012) The Cycad Pages.
  2. Medeiros & Stevenson (2012) Coralloid Roots and Nitrogen Fixation.
  3. Lambers, Hans (2016) Kwongan Foundation.
  4. Gerlach, Mark (2012) “The population structure and dynamics of Macrozamia riedlei within the Perth region” Honours thesis, Murdoch University.
  5. Barrett & Tay (2005) Perth Plants Perth: BGPA.
  6. Terry (2002) “Thrips: The Primeval Pollinators?” Thrips and Tospoviruses: Proceedings of the 7th International Symposium on Thysanoptera.
  7. Terry (2001) “Thrips and Weevils as Dual, Specialist Pollinators of the Australian Cycad Macrozamia communis (Zamiaceae)International Journal of Plant Biology vol.162, no.6.
  8. Williams & Adam (2010) The Flowering of Australia’s Rainforests: A Plant and Pollination Miscellany Vic: CSIRO Publishing.

    =^.^=

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