A special needs plant:
The Kitty Todd Nature Preserve is the Nature Conservancy’s 850 acre complex of open oak savanna and wet prairie lands located across the northern most portions of Ohio. Predominately porous acid sands, perched on top of a clay layer, the area historically has been an unforgiving environment for agriculture. Thus saved from the plow, the nutritionally poor lands remain mostly open wet prairie ecosystems with oak trees dotting the acreage. These acid sands are home to a wide population of rare and endangered plants, suited to these acidic conditions. Historically some twenty different populations of Platanthera ciliaris, commonly known as the orange fringed orchid were known across northern Ohio. Over the last 100 years of documentation, these twenty sites have now been reduced to one last known remaining colony. This initiative is an effort to help save the orange fringed orchid, native to these acids sands. With population numbers declining over recent years, a restoration plan using tissue culture techniques was started in 2011.
Micropropagation techniques have evolved over the past decades and are now known collectively as “tissue culture”. One of these approaches, in vitro asymbiotic seed germination is of particular interest to orchid propagators. The method has been previously demonstrated as highly effective in commercial tropical orchid propagation, and it is now widely practiced in native terrestrial orchid propagation. “In vitro” from the Latin definition – in glass – and “asymbiotic” referring to germination of the orchid seeds without the presence of a symbiotic fungus define this process. In nature, the orchid seeds must germinate symbiotically with a naturally occurring soil born fungus. In the asymbiotic approach, the fungus is replaced by a carefully controlled combination of chemicals and laboratory protocols. The popularized term “cloning” is sometimes confused with “tissue culture” however distinct differences should be noted, as it is just one of many available techniques. In cloning, exact duplicate copies are generated in the laboratory. In certain applications this may be desirable. However, in asymbiotic germination, namely seed culture, this is not the case. Since the starting point is a seed, either mature or immature, each seed carries the genetic diversity of its combined parents, and thus each seed in the seed capsule is genetically distinct from each other. This is of great importance when one wishes to repopulate existing wild stands, or start new sites when outplanting seedlings into nature.
Building on success:
Over the last two decades, the asymbiotic seed culture approach has been effectively used with many of our native terrestrial orchids. Many researchers have added to this growing database of laboratory protocols over the years. Recent work within the genus Cypripedium is but one of many examples. Through precise manipulation of media, recipes and laboratory protocols, many Cypripediums can be reliably germinated in the 80-100% ranges from mature seed protocols. Cypripedium reginae was the first native terrestrial orchid to be placed in the “easy to germinate” category.
At the Kitty Todd Preserve, no adult or juvenile plants were removed or damaged in this study. Only seed pods are required to start the asymbiotic seed cultures in the laboratory. Seeds were sown in the laboratory resulting in viable protocorms. Later, at the proper stage of development, these protocorms are ready for individual needle transfer under sterile lab conditions to re-plate containers. Early stage protocorms transfers are preferable, because the individual corms will quickly knit together forming a dense, unusable matt of rhizoidal root hairs if left in the germination tube.
Later, these individual corms develop on a modified agar recipe formulated to induce bud development while simultaneously encouraging roots to form. Many months later, we have viable seedlings.
The soil mix used for acclimating the seedlings from test tube to outdoor growing conditions is a sterilized blend. No soil borne mycorrhizae are used. In this way, there is no introduction of non-resident organisms to the Kitty Todd Nature Preserve. The seedlings will naturally be exposed to native, on-site mycorrhizae upon relocation to the preserve. The seedlings and the subsequent adult plants apparently may not require any special soil mycorrhizae to develop into long lived established plants. It should be noted, that the special soil mycorrhizae may only be required for the germination of seeds in the wild. Once the seedlings have developed to the green leaf stage the soil borne mycorrhizae’s role is in question. In controlled laboratory experiments, seedlings develop normally into full blooming adults without any mycorrhizae, returning year after year, increasing in size each season.
The long standing acceptance of the mutualistic, symbiotic fungal/orchid relationship is currently being reviewed by scientists. Several researchers now believe that the fungal mycorrhizae may indeed actually be acting more as a tolerated parasite in the adult orchid plants, then as a symbiotic partner.
Platanthera ciliaris seedlings develop quickly upon outplanting. Acclimation protocols to soil conditions are routine and trouble free. Transplants will produce flower brackets and set blooms in the first or second season out of test tube. Current information points to approximately seven year adult life cycle.
The first out-planting of seedlings is scheduled for spring, 2012 at Kitty Todd.
R. Price – Great Lakes Orchids, LLC