New Member Lesson 2- Orchid Growth

What is an orchid? In botanical terms, an orchid is a perennial herb, which means it is a plant that will grow for more than one year and has no woody structures. We don’t think of orchids as perennials because the tropical and sub-tropical orchids we raise indoors grow and bloom year-round. But hardy orchids which grow outdoors in temperate and colder climates go dormant during the winter months like any other perennial plant. Orchids have three sepals and three petals with one of the petals modified into a labellum or lip. They also have both the male and female reproductive parts on a single structure called a column.

Orchidaceae is a unique family of flowering plants in that it has members that grow in the air, in the ground, and under the ground. Most orchids are epiphytic, grow on a tree, or lithophytic, grow on a rock. Remember we talked about the event roughly 35 million years ago where orchids moved into growing in the canopy? The lack of competition in their new location gave these orchid genera free reign to propagate and diversify. The second largest group of orchids are the terrestrial and semiterrestrial. For the most part, this group of orchids kept their roots firmly anchored in the ground. An example of a terrestrial orchid is the hardy orchid Cypripedium acaule that we mentioned in Lesson 1. An example of a semi-terrestrial are some species in the genus Cymbidium. In nature, a semiterrestrial grows in a very loose mixture of leaf litter on the forest floor. Finally, we come to the oddity of the underground orchids. Rhizanthella gardneri, or the Western Australian Underground Orchid, is a mass of roots, no leaves, that grows underground usually near Ficus bushes. The fungi and bacteria living on the Ficus bush roots do all the work for the orchid by breaking down the inorganic and organic matter in the soil into chemicals and nutrients the orchid roots can absorb.

The second type of growth habit is sympodial which is where the orchid grows outwards. Each year, new shoots appear from a rhizome which is located at or under the surface of the medium. Some sympodial orchids, like the Oncidium pictured here, grow outwards in all directions. Certain Cattleya orchids, however, grow linearly in a single line, with a new growth appearing each year at one end and the oldest growth on the opposite end. Most sympodial orchids store their water and nutrients in their leaves, roots, and storage structures called pseudobulbs. Some pseudobulbs are very obvious, such as the ones on the Oncidium. Other genera have pseudobulbs that are not so obvious; and some sympodial orchids, such as Paphiopedilum, have no pseudobulbs at all. The one advantage of some sympodial orchids is that if the plant is large enough, with a minimum of 8 to 10 growths, it can be divided into two plants.

Grab some popcorn, relax in your favorite chair, and head to the “Webinar” section of the AOS website. This can be reached in two different ways. The easiest is to click on your account icon in the upper right corner of the home page and scroll down to “Member-Only Webinars”. You can also go to the “All About Orchids” tab and click on “Orchid Webinars” in the bottom of the right column. Both links will take you to the webinar main page.

The AOS offers webinars, such as the Greenhouse Chats, which are open to anyone coming to the website. Greenhouse Chats are hosted by Dr. Ron McHatton and occur nine months out of the year. Generally, these can be watched live during the first week of each month. Anyone can submit a question and orchid pictures of your orchid to Ron at greenhousechat@aos.org. One of the great things about these webinars is that they are reviewed by a volunteer and indexed with the topics covered. The indexing can be found by clicking on the “Learn More” tab. The indexed topics will also come up in a site search.

Members-only webinars are also offered live, usually the second week of the month for 10 months out of the year. These webinars are on varying orchid topics and are presented by a variety of Orchidists. Click the “Register Now” button to register to see these webinars presented live. A GoToWebinar link will be sent back.

Once presented live, both types of webinars will be posted on the website for future viewing. To find past webinars, scroll to the bottom of the Webinar Main Page where several are shown, or click the “see our full index in list form here” link at the top of the page. This will bring you to a list that can be sorted by any of the column headings.