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Cycad and podocarp care

Podocarpaceae (podocarps in English) is a very diverse family of conifers mainly existing in the southern hemisphere. They dominated the antarctic forest before the time of the dinosaurs, and remain in the cooler regions of the South America, Australasia and the Philippines. New Caledonia in particular has many native plants which survive little changed from the time when podocarp conifer forests covered Antarctica, nearby islands, and Southern continents.

Today, I cleaned the moldy leaves of the podocarp called Retrophyllum minus. This small tree-sized conifer has roots that prefer to grow in running water! It is the only conifer know to do so. The greenhouse has two small trees in its collection, both sitting together in a small pool of bubbling water.

Retrophyllum minus (Podocarpaceae)

To clean the plants, I lifted the pots out from the water pool onto a stool at about knee-height. I could access all of the needle-like leaves with a sponge of soapy water. Thankfully, the leaves were pretty tough and tolerated the abuse. Finally, I rinsed the entire trees with a douse of fresh water before replacing them back into the pool. 

Another plant which used to dominate plant life in much of the world before the time of the dinosaurs is the group known as cycads. These plants look superficially like palms or ferns, but are not closely related to either group. Cycads are gymnosperms, like conifers, they are not flowering plants. They have seed cones which are fertilized by particular insects (which leaves them susceptible to habitat loss and climate change). Existing species remain in Central and South America, as well as tropical regions of Asia. Fossilized plants are known to exist in parts of the Black Hills of South Dakota.

Today, I cleaned parasitic mealybug insects off the leaves of one of the large cycads in the greenhouse collection. The plant is called Ceratozamia robusta (in the family Zamiaceae), native to tropical parts of Mexico and Central America. This plant is threatened by habitat loss.

The cycad Ceratozamia robusta (family Zamiaceae)

Using a tall footstool. I used a spray of isopropyl alcohol (35% solution) and a loo brush to wipe down fronds. The leaflets have very sharp edges and spines. I often have bloody forearms after caring for this type of plant. Today, I used long rubber gloves to handle the fronds. The mealybugs are truly amazing creatures to be able to suck sap and benefit from this sturdy plant with leaflets and stems as tough as hard plastic.







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