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SO Gardening — Sept 2

Sunday, September 02, 2018

Dear Orchid Doc:

Can you tell me what the secretions are that some orchid plants put out around the stems of their flowers? Sometimes, it is sticky and develops sooty mould like on Grammatopyllum scriptum. On other orchids, such as Oncidium Sharry Baby, it is more watery. I find it seems to appear in the morning.



Dear Tessa:

The secretion is simply plant sap, called honeydew, which is secreted by healthy plants. It is, as you note, basically sugar water, and can lead to sooty mould. This is why sooty mould can often be an indicator of sucking insects, which feed on this same sap, supplied to them by the plant's osmotic pressure. When the pressure is sufficiently high, the sap passes right through the bugs' digestive systems, resulting in conditions favourable for sooty mould.


Dear Orchid Doc:

Is it possible to safely store, and keep viable, cymbidium pollen? How long will it remain in good condition and how should it be stored? I would like to do some standard cymbidium breeding, but one cultivar, which is in spike, has not yet bloomed and I want to use it as the capsule parent plant.



Dear Tom:

For the short time you have in mind, remove the pollen, wrap in clean paper and store in a cool, dry place. Small Post-its can be folded up to store pollen. The pollen will keep this way for at least a year. For longer storage, the use of a dessicant is recommended. We have stored pollen in a stoppered test tube, with desiccant in the bottom held in by cotton. Pollen will keep for some years this way. Be sure to label and date the packets.


Dear Orchid Doc:

What makes an orchid an orchid?



Dear Kevin:

When many people see orchids, they can't imagine what so many diverse plants have in common that makes them all orchids. They look so different! You have to closely examine the flower for the answers. If you study the inner part of the flower, you'll see a clublike structure that houses the male and female flower parts (stamens and pistils) called the column. All orchids have this unique structure. Most also have a large and conspicuous centre petal called a lip.


Dear Orchid Doc:

Are orchids fragrant?



Dear Kim:

Not all orchids are fragrant, but many are. A wonderful aspect of orchid fragrance is their range of scents. Some smell like other flowers (carnations, jasmine, gardenia, rose), while others have the scents of spices and foods (vanilla, citrus, cloves, chocolate, coconut, licorice, honey, cinnamon, grapes).

Some orchids even reek! These are orchids that are pollinated by flies and other insects attracted to carrion (rotted meat). Fortunately, very few orchids fall in this category and they're easy to pick out when selecting orchids from a grower's greenhouse.