Michael Cory teaching the crew about Darwin's Orchid

I’m learning to give tours at the Volunteer Park Conservatory, which involves a number of 2-hour long sessions with the gardeners, teaching us about the plants and the history of the conservatory. Last weekend’s course was on orchids - there’s a lot of reading material out there, so rather than write a comprehensive introduction, I thought I’d share some of my notes and photos from getting up close to the flowers and examining the pollen and the roots and etc.

Food

  • Vanilla is an orchid! It’s possible (but difficult) to grow yourself - the bean pods are what we use for flavoring.
  • Salep is the other food product we make from orchids - it’s a flour made from the roots of some orchids, and it’s highly water absorbant - it’s largely used in Turkey to delay ice cream from melting.

Epiphytes

  • While not all orchids are epiphytes, many of them are. They originated growing on the surfaces of trees, and they’re used to having sporadic water cycles where they get drenched from rain, and then totally dry out for a long period.
  • Common (bad) advice is to put ice cubes on the soil - the rain cycle is why most orchids don’t actually do well with this approach. They don’t want to be constantly damp or their roots will rot.

Reproduction

While many plants can be considered one ‘gender’, most orchids contain both halves of the reproductive process - the stamen (producing the pollen), and the pistil (which is fertilized by the pollen). The pistil + stamen are united into the ‘column’, which sits (typically) opposite the lip, at the top of the flower.

The pollen is a solid mass, rather than a loose powder. It’s sticky, in the hopes that the bee/moth/etc that picks it up will visit another flower and deliver it. Because orchid pollination is a high risk/high reward payoff, they produce many tiny seeds, all lacking in nutrients (but all very cool). The seeds are then blown by the wind to hopefully land somewhere with a fungi it can partner up symbiotically with

Phalaenopsis (the kind you most commonly find in stores)

Identification

For a plant with over 20,000 natural species (not including hybrids), orchids have a surprising amount in common with one another! There are a lot of differences, to be sure, and Dendrobiums in particular are quite different looking from some of the more common ones we see in stores, but it kind of amazes me that there are some easy identification tricks.

All orchids have bilateral symmetry - you could draw a vertical line down the center and it would neatly split. Obviously in practice, petals may get damaged and so not appear perfectly symmetrical.

Orchids also all have:

  • 3 sepals (the things that cover the flower when its in a bud)
  • 3 petals (2 regular ones, + “the lip” which is a modified one)
Cattleya (...I think). The purple part is the lip, and it contains the column inside it.

Keikis

We were able to step into the back production area of the greenhouse, and there we found a number of orchids with keikis (baby offshoots). These can be simply removed from the plant and repotted! We were (very generously) given some to take home ourselves. These are from a Dendrobium.

Orchid keikis (kay-kee)!

Lady Slipper

There are some cool pitcher tube style orchids (approximately 165 species) that use a similar mechanism to some carniverous plants of having dowpointed (retrorse) hairs that prevent the insect from crawling out the way they came. In the case of the Lady Slipper orchids, they instead force the insects to crawl up past the stamen, where they can collect or deposit pollen, to fertilize the flower.

Lady Slipper Orchids