EPOW - Ecology Picture of the Week

Jurassic Cycad Park

Cycad (Cycas armstrongii) female plant, Family Cycadaceae
Manton Dam Recreation Area, Northern Territory, Australia

Explanation:  No dinosaurs here (except for birds), but enjoy this peek back in time.  These are cycads, distant and ancient relatives of ferns and palms, that flourished during the Jurassic period 200-145 million years ago.

Cycad plants are male and female.  In the photo series above, we see a sequence of the development of female cycads, which have seed-bearing cones that require pollination.  The female bears fully developed seeds on sporophylls that droop from the top of the mostly fibrous stalk.  Seeds of this species mature in about a year toward the end of the dry season.  

Female (left) and male (right) stems of Cycas armstronii in Howard Springs Nature Park, Northern Territory, Australia.

Cycads grow slowly and prefer well-drained sites, such as in this open woodland.  

Their seeds are consumed, and thus the plant is dispersed, by emus.  This is an interesting symbiosis, especially if you think of emus as a form of modern-day dinosaur (or at least of that ancient lineage).  It is a Jurassic plant being consumed and dispersed by the distant relative of a Jurassic dinosaur.  

There are about 300 species of cycads occurring around the world mostly in the tropics and southern hemisphere.  

Male cone of Cycas armstrongii.

The seeds of the female plant are highly toxic, and were known to do in a number of early settlers.  

But the aborigines of the region learned to detoxify the seeds, apparently through multiple washings and leachings of the toxins.  They also made flour from the seeds, and burned areas to promote growth and seeding of cycads.  Such is the wisdom of traditional ecological knowledge.

A "fledgling" Cycas armstongii growing from a seed, yet to have developed its characteristic stalk.  

Many cycads are threatened or endangered from overharvesting for the horticultural trade, or clearing for pastures or development.

Although still relatively common, Cycas armstrongii is listed in the IUCN Red List for Threatened Species as "vulnerable" because of recent declines and ongoing threats from increased fire caused by the spread of invasive grasses in Northern Territory, Australia.