Journal Number 89
December 2003

NOTES etc

A contributor to a native orchid chat group wrote,

"I was recently at a site in Central New York State (USA) that is supposed to have Platanthera orbiculata and/or P. macrophylla. They have been described to me as species that will often have leaves, but don't flower except every so often. Now is the time when the flowering is supposed to be at its peak, but after finding around 30 or more plants in a few acres area, no flower spikes have been found.

Is it possible that a whole group may avoid flowering, or is it possible that a very cool spring with a deep snow cover over the winter would radically delay the flowering time? I know that many other terrestrial orchids will hide underground for many years, others have leaves but not flowers.

The leaves I have found range from medium/small to very large, so it doesn't seem that health and age have anything to do with them not flowering. Some of the leaves are very healthy looking".

Another added, "I monitor Platanthera psycodes here in the southern edge of its range in northern Illinois. Seven years ago there were almost a hundred plants between the two different sites I monitor. Last year, after we had three summers of drought, there were two plants per site. This year, a very rainy year overall, there was only one plant on one site and that had been eaten by a deer. If anyone can help me figure out some strategies for not losing these populations entirely in these sites, I would greatly appreciate it. Or - do you think they are just gone, since there were no reproductives this year?"

From the US, "Warren Stoutamire and others have observed that many terrestrial species can spend a lot of time underground, perhaps in a saprophytic state and then appear again. Professor Gill at University of Maryland carefully observed Cypripedium acaule being 'dormant' for many years before reappearing. Platanthera leucophaea may exist in many early seedling stages for years before making an appearance. It is possible that 'they aren't dead, only sleeping'".

And, "I too tend to be optimistic - with 100 flowering plants seven years ago (i.e. in 1996) and
a few plants still flowering after three summers of drought, more plants surely have survived underground. With this year's rain, the coming years probably will show reduced, but not eradicated populations".

And, "I think you have many dormant plants that remained underground to build up their reserves. The next few years will give you the answer so keep up hope".

And, from the original contributor, "I earnestly hope that the population is not lost, too! As far as I know, the last data collection took place eight years ago, before I and my monitoring partner went out there last year to survey the sites and look for plants. Because it is such sensitive habitat, we did not trample everywhere, but focused our attention on the area where they had been found previously. I am wondering whether the deer eating the one plant will have killed it or whether there was possibility of it coming back next year".

And finally, from UK, "I don't have much knowledge about USA Platantheras, but it is possible that
they may respond to drought in a similar way to our Bee Orchids. If you want to see some
information on the response of Bee Orchids please look at our website (http://fp.orchidmagic.f9.co.uk) - in the Favourites section click on the thumbnail on the left
of the top row."

"The height of the Bee orchid varies from about 7-70cm and the number of flowers per stem from 2 to more than 12. Mowing or grazing of stems before seed production usually results in more buds the following year. The sepals are typically 10-20mm long and the leaves, which persist until after flowering in June/July (given enough water), appear above ground in September/October in England; the leaf rosette is close to the ground.

November is usually the easiest time to find Bee orchid plants as the leaves have a distinctive silvery green colour. In cultivation, given access to fertiliser and lower light levels, the leaves become a deeper green and loose much of their silvery appearance. It produces one to three new tubers each year, if it does not become too dry during flowering. If it aborts its flowers and sets no seed it is a clear sign that it has been too dry and that it will not have formed a significant replacement tuber. It is believed that if it becomes too dry it can form tiny tubers at or near the ends of its roots and that these then take a number of years to reach flowering size.

When raised from seed, with or without fungus, it is possible for Bee orchids to reach flowering size in 2 years, in nature, with less than ideal conditions, it may take many years, depending upon water supply. Plants that are watered during droughts flower every year with a large number of flowers per spike and can produce more than one tuber per year.

Although the tuber is regarded primarily as a food store by many people, in a wet autumn the tuber can become very large (3 x 4 cm or more), even though a tuber smaller than 1 x 1.5 cm can produce flowers. This suggests that the tuber may be storing large quantities of water whenever possible. I have transplanted a number of Bee orchids from threatened locations to safe ones (with the appropriate permissions) and I have not seen any evidence for deep roots like those found in Dactylorhizas, or even any roots that penetrate below the bottom of the tuber. The spread of the roots is usually very small, only a few times the diameter of a large tuber.

The combination of lack of water during flowering and the tiny root system is probably
responsible for the belief in England that Bee orchids are short-lived (or only flower once) and
are prone to disappear and reappear randomly.

"The following is quoted verbatim from an email that I received, 'The problem with O. apifera is
that it is actually polycarpic, not monocarpic as was previously thought. This means that the
same tuber can lie dormant up to a number of years and then flower, giving the casual observer
the impression that it is a first year coloniser.

The seeds may have germinated years ago but development halted as it entered the dormant phase. The population dynamics of this plant are erratic and require a long term study to fully understand (20+ years).

My research did involve an area of industrial land with this species (now developed) and only 6 were found in the 1st year while in the following year over 40 were seen. This species favours this type of habitat, since competition is low. But do not be alarmed if few appear next year, as was previously explained, this is a result of dormancy, induced by stress of reproduction, herbivory and/or climate. But consideration should be made for changing associated species assemblage through time (succession)'.

"I am not sure if true dormancy takes place, or if replacement tubers are made each year, or even
if a combination of these things plus the earlier suggestion of mini-tubers. There is still much to learn about this species."