reference now will be made to the embodiments of the invention , one or more examples of which are set forth below . each example is provided by way of explanation of the invention , not as a limitation of the invention . in fact , it will be apparent to those skilled in the art that various modifications and variations can be made in this invention without departing from the scope or spirit of the invention . for instance , features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment . thus , it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents . other objects , features and aspects of the present invention are disclosed in or are obvious from the following detailed description . it is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only , and is not intended as limiting the broader aspects of the present invention , which broader aspects are embodied in the exemplary constructions . in the high volume production of plants for consumer and agricultural uses , it is critical to develop a system for containing and propagating plant material that is easy , inexpensive and effective in propagating the plants . stage one of plant propagation is generally the initiation stage in which a shoot or a bulb is initiated in the enclosure of the invention . in stage two of development , plants uptake nutrients and growth regulators to encourage rapidly dividing cells within the plant . in the first two stages of plant growth , therefore , there are high metabolic requirements for energy consumption . in general , during the first two stages of growth , the plant tissue is not capable of carrying out adequate photosynthesis to meet this high demand for energy . the initial growth of tissue in the enclosures of the invention is accomplished heterotrophically . heterotrophic or photomixotrophic growth is growth in which the organism obtains nourishment and energy from the ingestion and break down of organic matter . during this phase , the plant tissue is typically exposed to adequate light intensity to sustain growth . the organic carbon is usually obtained from sugars such as sucrose . in general , micropropagation is commonly completed in a mist or fog enclosure in a greenhouse . these environments provide haven for biotic pests . therefore it is common for the clean products of a lab to be shipped and sold in septic media from a mist or fog house . furthermore , water is constantly percolated through the soilless media , so the small plants with rudimentary roots do not dessicate . the percolation of water leaches the soluble fertilizer salts down through the media profile , making fertilizer scarce for the rudimentary root system . therefore , plants from a mist or fog house are also nutrient starved when delivered to the end user . in the third stage of plant growth , leaves and shoots expand and the plant tissue develops the capability of photosynthesizing . that is , the plant tissue , when exposed to light , gases , water and essential nutrients , derives energy through the process of photosynthesis . photoautotrophic growth occurs when the plant organism synthesizes organic nutrients by deriving energy from light . that is , once photoautotrophic growth begins , the plant tissue becomes capable of making its own food in sufficient quantity to support photoautotrophic growth . generally , plants need oxygen , carbon dioxide , water , nutrients , and light for carrying out respiration and growth processes . oxygen , carbon dioxide and light can be provided to the plant material from the atmosphere . during photosynthesis , besides carbon dioxide and light energy , the plant material needs water , in order to synthesize carbohydrates . however , the liquid growth media can include water as an ingredient in concentrations sufficient to support photoautotrophic growth . as described , plants require carbon dioxide in order to carry out photosynthesis for producing carbohydrates . in the past , when sealed in containers , plants have been slow to photosynthesize . a possible cause for this deficiency may result from the depletion of carbon dioxide within the container . in order to overcome this problem , the plant propagation system can optionally include enrichment from an external carbon dioxide source . turning to fig1 a sealed enclosure 21 is shown having a generally transparent exterior . a first wall 22 is opposite a second wall 23 , and an inner space 24 is between the first wall 22 and the second wall 23 . furthermore , an outer surface 25 is provided on the outside of the enclosure 21 . plant material 26 , in the form of one or more propagules , is provided inside the sealed enclosure 21 . a reservoir 27 of liquid nutrient solution is also provided in the sealed enclosure 21 . injection area 28 comprises generally one corner of the enclosure , into which a syringe may be introduced to provide sterile gasses through a filter capsule to the interior of the sealed enclosure 21 after the enclosure is sealed with plant material placed inside . once gasses are provided to the sealed enclosure in the appropriate volume and pressure , the sealed enclosure 21 may be sealed at sealing line 29 in order to isolate the hole made in the sealed area 28 from the rest of the sealed enclosure 21 , so that the sealed enclosure 21 may be “ resealed ” after injecting gas into the inner space 24 of the enclosure 21 . in fig1 a , a sealed enclosure 121 is provided which shows an alternate embodiment of the invention . in this embodiment , a first wall 122 and a second wall 123 is provided , with an inner space 124 separating said walls . an outer surface 125 is also provided . plant material 126 is positioned between the first wall 122 and the second wall 123 . furthermore , a reservoir 127 is provided near the lower portion of the enclosure 121 . in this embodiment , a gas diffusion membrane vent 130 is provided upon the first wall 122 of the enclosure . the gas diffusion membrane vent 130 provides an area in which gasses may be transferred into the inner space 124 of the enclosure 121 . however , the membrane vent 130 also serves as a screen against biological contaminants or pests that might otherwise enter the enclosure 121 through the membrane vent 130 . furthermore , the enclosure of fig1 a may be folded over the membrane vent 130 so that water loss is minimized at a time that carbon dioxide in the headspace is not so important . the heterotrophic or photomixotrophic phase of growth is an example . fig2 shows a method of transporting the enclosures of the invention . in fig2 a plurality of enclosures 202 a - h are shown arranged in a parallel fashion within a transport box 200 . thus , when the enclosures are filled with plant material , and provided with the appropriate amount of gas and nutrient solution , they may be transported from a laboratory environment to another laboratory or greenhouse environment , for example . in other examples , the enclosures 202 a - h could be used to transport plant seedlings or other plant material from a greenhouse environment to the field . in some instances , it might be possible to transport plant material directly from the laboratory to the field . in any event , transportation of plant seedlings may be easily and quickly accomplished using the enclosures of the invention . a box lid 201 optionally may be provided to support the upper surface over the enclosures 202 a - h during transport . fig3 shows an alternate embodiment of the invention in which an enclosure 300 is comprised of at least four walls and a bottom portion . a gusset 301 and gusset 302 are provided on each side of the enclosure 300 , and plant material 303 is shown within the enclosure 300 . an optional membrane vent 304 is shown near the top of the enclosure 300 , and the top margin of the enclosure may be heat sealed along sealed margin 305 . fig3 a shows the embodiment of fig3 in which the top membrane vention of the enclosure 300 has been folded over to partially block the flow of gasses into or out of the membrane vent 304 . thus , for example it might be possible to fill the enclosure 300 with an appropriate amount of nutrient solution 307 , and the correct gasses for healthy plant growth . then , the plants could receive gasses ( i . e . : respire ) in the laboratory environment while they are growing , and just prior to transport the top portion of the enclosure 300 could be folded over to avoid gas exchange into the enclosure 300 during transport . furthermore , folding over the enclosure 300 during transport would perhaps pack the enclosure 300 in a more compact arrangement for shipping and transport . fig4 shows a partial cross - section of a tray assembly 320 of the invention . in a greenhouse or outdoor environment , it would be possible to place enclosures 321 and / or 300 within a support tray 322 to receive direct sunlight once the plants are capable of photosynthesizing for themselves . in order to reduce the excess heat generated by intense sunlight upon the enclosure 321 , a cooling fluid 323 could be provided within the support tray 322 , and allowed to flow past enclosure 321 while it rests in the support tray . thus , light could easily impinge upon the enclosure 321 , and it would be naturally cooled by the cooling fluid 323 passing within the support tray 322 . in a commercial environment , a large number of enclosures 321 could be placed in series along support trays which are substantial in their length . support tray 322 could be comprised of an insulated material such as styrofoam or fiberglass . in fig4 a , an embodiment showing a commercial use of the invention is shown in which numerous support trays 322 a - d are shown arranged in parallel . these support trays could each support tens or hundreds of enclosures 321 a - d and / or 300 along their inner surfaces . in some embodiments , it might be possible to provide support trays 322 a - d in a matrix having both a vertical and horizontal component . in other embodiments , the support trays could be placed in a rotating turret assembly which rotates according to the amount of light that impinges upon the trays during the path of the sun across the sky . such mechanisms could be timed to receive an appropriate amount of light upon each support tray , and an apparatus could easily be devised by a person of skill in the art that would provide an appropriate current of cooling fluid along each support tray . fig5 shows an end view of a support tray 401 which has within it an enclosure 402 that contains plant material 403 . a cooling fluid 404 is shown in the bottom of the support tray 401 . the end view shown in fig5 is an end view of the support trays shown in fig4 and 4a . in fig6 on the other hand , an alternate embodiment is shown . in that figure , a support tray 501 which extends in a tubular fashion nearly all the way to the top membrane vention of enclosure 502 on each side is seen . by almost completely encircling the enclosure 502 , an enclosed space 507 a and 507 b is formed on each respective side of the enclosure 502 . likewise , cooling fluid 504 is shown near the bottom of fig6 . plant material 503 is shown within the enclosure 502 . membrane vent 511 allows carbon dioxide to enter the enclosed spaces 507 a - b . a partial seal 512 is provided as the buoyant enclosure 502 is raised to contact the tray 501 at partial seal 512 . importantly , the embodiment shown in fig6 would be capable of receiving carbon dioxide or other gaseous injection into the enclosed space 507 a or 507 b to provide , for example , a carbon dioxide enriched environment surrounding the enclosure 502 . several different embodiments could be devised by a person of skill in the art , and it would be possible to provide the enclosure 502 at a higher level so that the plant material received direct sunlight , or in other cases indirect sunlight coming through the top of the tray 501 would be sufficient . furthermore , plexiglass panels could be provided along the walls of the tray 501 to allow sunlight to come in , but still maintain an enclosed space 507 a and 507 b for facilitating an enriched gaseous environment . when using enclosures having a membrane vent on the surface of the enclosure , enriched carbon dioxide gas would be allowed to diffuse through the membrane vent , perhaps accelerating plant growth . in other embodiments , it would be possible to provide a gear sprocket or other mechanical device , which could be attached to the end of the thermally buffered enclosure . such a device could be constructed by a person of skill in the art , and would be capable of facilitating shoot canopies to be manipulated so that leaves of the plant are coincident or oblique with respect to direct sunlight . this sort of device would be useful to manage light and heat , cloud cover , seasons , and diurinal variation . it could rotate the apparatus along rotation tilt axis 600 to face the plant material toward or away from the angle of solar incidence . the rotation could be up to about 45 ° in one direction , and up to about 45 ° in the other direction ( i . e . : deviation from vertical ). a further optional feature that can be added to the plant propagation system is a spectral filter for filtering the light before it reaches the plant material . filtering can be accomplished using colored or shaded flexible film . films that admit only light of preferred wavelength also may be employed . light reflective film may also be used . for instance , when plants first arrive from a laboratory , solar radiation may be too intense for chloroplasts developed under low light conditions . also , some plants tend to grow better when only exposed to light in a particular range of wavelengths . particularly , red light has been demonstrated to increase growth rates in some plant species . as constructed , the sealed enclosure is generally impermeable to biological contaminants . as such , plant material , enclosed within the sealed enclosures , can receive light , oxygen , carbon dioxide , water , nutrients and other growth and respiratory needs while remaining shielded against pathogenic microorganisms . the plant material such as vegetative buds , bulbets , miocrotubers , or somatic embryos can be placed within the sealed vessels when capable of forming shoots , but ill - suited for autotrophic growth . at this stage , the sealed vessel can be exposed to a liquid solution containing organic carbon for the heterotrophic or photomixotrophic growth and development of the plant . once developed into a small plant capable of surviving in soil , the plant material can be transplanted as desired . consequently , the plant material can be developed into a photosynthetic plantlet without ever being removed from the sealed enclosures . further , the sealed vessels can be used to facilitate transportation of the plant material to any desired location . for instance , some material is prohibited from international commerce due to possible accidental inclusions of biological contaminants on plant tissue or media . as plants in this invention are produced free from biotic contaminants , and on sterile substrata , quarantine regulations would be satisfied . it is understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only , and is not intended as limiting the broader aspects of the present invention , which broader aspects are embodied in the exemplary constructions . the invention is shown by example in the appended claims .
a plant propagation apparatus is disclosed which comprises a flexible transparent enclosure . the enclosure is disposable , and could be formed of a polymer such as polyethylene . the enclosure would have at least two walls , formed of flexible material that facilitates transmission of light through the walls . plant material is sealed within the enclosure , and nutrient solution is made available within the sealed enclosure for the plant . the enclosure is a low cost and effective method for propagating young plants and transporting them between the laboratory environment and a greenhouse or field . the enclosure may be configured to receive gas or carbon dioxide on its inner surface to a predetermined level of pressure , thereby affording the enclosure a flexible but stiff mechanical resistance that protects the young plant while it is growing .