Gifts and Volunteers Moderator: Marilyn Light Wednesday 9/14/05 |
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MarilyninOttawa In early 1990, I received a fruit of Sobralia xantholeuca. I was informed that the plants would be a modest size at maturity. I had little knowledge of the species but set out to learn what I could. I wanted to ultimately flower a seedling to confirm the identity, and to follow the flower aging process. Sobralias have spirally arranged plicate leaves, terminal inflorescence atop bamboo-like canes, and large, strongly ribbed capsules. My capsule was 85 × 25 mm. The fruit was superficially infected and partially split so I surface sterilized the seeds for 10 minutes in 1:20 bleach solution before sowing them on March 3. The seeds were very large (almost a centimeter long) with prominent embryos. You can view typical Sobralia seeds in Nina Rach's Sobralia pages. I used several media formulations available at the time including G&B Mother Flask V which contains charcoal. This proved to be the best. Embryos greened within the first week. The first leaf was produced a week later. I learned two interesting things. The seeds germinated more like grass seeds than a typical orchid: they produced a coleoptile from which the first leaf emerged. I also learned that the seeds, while vigorous germinators, were short-lived. I could not repeat experiments. [coleoptile: The protective sheath that surrounds the young shoot tip of a grass during its passage through the soil to the surface. Although of relatively simple structure, most coleoptiles are very sensitive to light, ensuring that seedlings grow upwards.] I distributed seedlings to orchid society members. While this species is a compact grower, blooming size plants fill an 8-in pot! I learned that one of these plants had flowered in 2004. Over the years, I had tried growing the plant under lights but it seemed to prefer a cool windowsill over the winter months and semi-shade outdoors during the summer. I was delighted to see the telltale sign of a swelling stem tip in spring. This is the first bud shortly before opening. My first flower opened before 6:30 am on June 17, 2005. The flower smelled of stearate (like candles) by 8 am, stronger by 10:30 am. The bright yellow flower measured 9 cm wide by 11 cm long. Isn't it gorgeous!!! Note that the flower can last several days and expands during that time. The color does not noticeably fade. This is a modest plant and well behaved as it grows up and not too much sideways. Try it! The petals and sepals were reflexed at the tips. The ruffled lip was somewhat crumpled, measuring 6 cm wide by 9 cm long. Side view I compared this to what was illustrated in books and at Nina Rach's Sobralia pages. As far as I can determine, what I have is typical of Sob. xantholeuca. My first flower remained fresh and fragrant until 10 am on June 20. By then, the segments had become less reflexed and the flower had expanded to 13 cm square. It began wilting by midday when it was still slightly fragrant. This first flower remained fresh for approximately 75 hours. During this time it was exposed to a total maximum ambient temperature of 77 deg C (range: 15.3-20C) and a total minimum ambient temperature of 46C (range: 10.4-12.1C). We removed this flower for dissection and photographic purposes. A second flower opened before 6:30 am on June 26 or 11 days after the first. The flower was self-pollinated at 1:30 pm but the flower only faded fully two days later. While open, the flower was exposed to an average maximum daily temperature of 31.8C and minimum of 18.7C but of course, it had been pollinated which could lead to premature aging. Flower dissection: We removed the perianth to reveal the column and lip. [perianth: in botany, a collective term for the outer whorls of the flower, which protect the reproductive parts during development. In most dicotyledons the perianth is composed of two distinct whorls, the calyx of sepals and the corolla of petals, whereas in many monocotyledons the sepals and petals are indistinguishable and the segments of the perianth are then known individually as tepals.] We then removed the lip so to be able to examine the column more closely. The column was removed from the plant so as to photograph the underside. A closeup view of the column tip reveals the stigma and the anther cap. The anther cap was gently displaced to reveal the pollinia within. Once the pollinia are removed, we can see the associated structures more clearly. Finally, we see the pollinia separated from the anther cap. Note that there are two large and two smaller pollinia structures. The pollen is mealy. A third flower bud appeared in early July but the developing fruit was still hidden by bracts. This third and last flower opened on July 17 or one month after the first. It was smaller and lasted only two days. This third bloom was exposed to an average maximum of 29.3C and minimum of 22C while open. My experience is limited to these three blooms but flower aging could be affected by temperature, something that I intend to follow-up next year. [http://www.onlineconversion.com/temperature.htm] The fruit began elongating rapidly from 10 days after pollination. On July 20 (24 days post-pollination) the fruit was 90 mm long. Increase in girth ceased for about a week in early August which in my experience is the interval when fertilization is happening. This was 40 to 50 days post pollination. After fertilization, capsule growth resumes and will continue until the seeds are matured. As of today, the fruit measures 11.5 mm long by 23 mm wide. According to my 1990 notes, this should be when the fruit reaches 25 mm diameter. Once the seeds are ready, I will sow them on a range of media containing charcoal. Knowing that the seeds are short-lived, I plan to have replicates so that all germination stages can be photographed. Sobralia xantholeuca is a desirable showy species that is relatively easy to grow. It prefers an open mix of bark/coconut chips and humus or compost. Watering is a daily requirement as is weekly feeding year round. The plants tolerate a range of light and temperature conditions but seem to thrive in summer heat and humidity. It is possible that cool nights induce flowering in early summer. The specific epithet was published in 1885 but it was clearly known in cultivation before then. There are 11 registered hybrids, the first being Sob. Wiganiae (1856) and the most recent, Sob. Songbird (2004). Various sources tell us that fruits dehisce at 68 days to 8-10 months post-pollination. I look forward to reporting the capsule age at dehiscence but suspect that it will be less than 100 days. Next comes a story about a 'volunteer'. Have you ever wondered what it would be like to have wild orchids pop up in your garden or greenhouse? I have had reed stem Epidendrums germinate in a shadehouse and Spathoglottis germinate in pots of other plants but these were all plants in cultivation. Imagine my surprise when in 2003, I found a tiny leafy rosette of what I assumed was a Spiranthes growing in a pot of aloes placed in my summer garden. I found another similar rosette in a pot of Cinnamon Yam nearby. The one thing in common was that the potting material, a commercial peat-perlite preparation. Where had the seeds come from? A peat bog was a possibility or maybe they had blown in. I had to shelter the Aloes pot from frost but the yam seedlings needed a cold rest. That pot was stored over winter in an unheated garage where the temperature dropped to -10C (14F). The aloes pot was stored in a cool room at 5 to 10C (41 to 50F). The Spiranthes in the cool room did not survive but the seedling stored cold in the garage survived with just the leaf tips dried. When the weather warmed, I placed this pot outdoors and watered it. Within a few days, the leaves began to expand and new leaves appeared. This rosette enlarged until some leaves began to lengthen. A flower spike emerged and flowers opened in August. It was Autumn Ladies Tresses, Spiranthes cernua. I compared the flower to that of another species which blooms at somewhat the same time, S. casei. It is clearly Spiranthes cernua which has a larger more open bloom. Last year, fruits formed and many seeds were produced. I prepared seed packets to test germination in other potting mixes. The few seeds left were scattered over the pot surface near the mother plant. Eventually, the pot was placed in the garage to overwinter. In spring 2005, two shoots emerged near the base of the old plant and three offsets appeared around the edge of the pot. Additionally, six tiny seedlings appeared where I had scattered seeds. That these were seedlings and not offsets was proven by carefully lifting the soil beneath the plants. Offsets have an obvious stolon connection. Seeds had germinated in the various packets but remain protocorms beneath the soil surface. What is most exciting is that this summer, I have found yet another new seedling in another garden pot prepared from the same batch of peat mix. I wonder if the peat mix is a seed source? How long can orchid seeds remain viable in the peat mix? This year's inflorescence had over 25 flowers and thus will provide many 'volunteers' with which to experiment. So you see, opportunities abound and opportunity does knock more than once. I am looking forward to learning more about the Sobralia and the Spiranthes which is yet another facet of orchid life. I am looking forward to growing more Sobralias, the smaller ones that is. There are some interesting species now in cultivation and not all have flowers lasting only a few hours. Any questions, comments?? John in Arcadia, Ca Marilyn, it really is interesting and maybe more of us should try when we have the opportunity. I would like to especially with the spiranthes but we do not get cold enough here so I would have to use more native species. Would Epipactis gigantea work? We have that close by here but at a much higher elevation. MarilyninOttawa John, if you visit Ecuagenera's site, they list quite a few Sobralias. Some are warm, intermediate or cool growing. The cold growing types could be challenging to flower unless you can give them the appropriate conditions. I am growing one now and find that it has no problem with our hot (30C) weather. Neither does it mind 5C. There are a number of US sources of cultivated plants. http://www.sborchid.com/Sobralia_xantholeuca.htm Steve_in_the_Adirondacks John in Arcadia, Ca. MarilyninOttawa Jade_in_GR MarilyninOttawa Jade_in_GR MarilyninOttawa There probably are natural controls. Last year, over 75% of Cyp fruits were attacked but this year, there are fewer than 10% damaged. This could be because of predation or other causes. The bottom line is the cyps still produce millions of seeds which is enough to maintain the population Steve_in_the_Adirondacks MarilyninOttawa Steve_in_the_Adirondacks -end |
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Prechat Handout Gifts and Volunteers Copyright Marilyn HS Light
They say that opportunity knocks but once but in reality, opportunities always abound. In the orchid sense, there are countless opportunities to learn and share, to assist and contribute, to turn an opportunity into a conservation experience. Such was my experience in the two instances discussed here. The first was a gift of seeds of Sobralia xantholeuca, and the second, a Spiranthes seedling found growing in a garden pot. This their story. SOBRALIA In early 1990, I received a fruit of Sobralia xantholeuca. I was informed that the plants would be a modest size at maturity. I had little knowledge of the species but set out to learn what I could. I wanted to ultimately flower a seedling to confirm the identity, and to follow the flower aging process. Sobralias have spirally arranged plicate leaves, terminal inflorescence atop bamboo-like canes, and large, strongly ribbed capsules. My capsule was 85 × 25 mm. The fruit was superficially infected and partially split so I surface sterilized the seeds for 10 minutes in 1:20 bleach solution before sowing them on March 3. The seeds were very large with prominent embryos. You can view typical Sobralia seeds in Nina Rach's Sobralia pages. http://sobralia.autrevie.com/Sobralia_spEcuadorWhite.html I used several media formulations available at the time including G&B Mother Flask V which contains charcoal. This proved to be the best. Embryos greened within the first week. The first leaf was produced a week later. I learned two interesting things. The seeds germinated more like grass seeds than a typical orchid: they produced a coleoptile from which the first leaf emerged. I also learned that the seeds, while vigorous germinators, were short-lived. I could not repeat experiments. I distributed seedlings to orchid society members. While this species is a compact grower, blooming size plants fill an 8-in pot! I learned that one of these plants had flowered in 2004. Over the years, I had tried growing the plant under lights but it seemed to prefer a cool windowsill over the winter months and semi-shade outdoors during the summer. I was delighted to see the telltale sign of a swelling stem tip in spring. My first flower opened before 6:30 am on June 17, 2005. The flower smelled of stearate (like candles) by 8 am, stronger by 10:30 am. The bright yellow flower measured 9 cm wide by 11 cm long. The petals and sepals were reflexed at the tips. The ruffled lip was somewhat crumpled, measuring 6 cm wide by 9 cm long. I compared this to what was illustrated in books and at Nina Rach's Sobralia pages. As far as I can determine, what I have is typical of the species. http://sobralia.autrevie.com/Sobralia_xantholeuca.html My first flower remained fresh and fragrant until 10 am on June 20. By then, the segments had become less reflexed and the flower had expanded to 13 cm square. It began wilting by midday when it was still slightly fragrant. This first flower remained fresh for approximately 75 hours. During this time it was exposed to a total maximum ambient temperature of 77 deg C (range: 15.3-20C) and a total minimum ambient temperature of 46C (range: 10.4-12.1C). We removed this flower for dissection and photographic purposes. A second flower opened before 6:30 am on June 26 or 11 days after the first. The flower was self-pollinated at 1:30 pm but the flower only faded fully two days later. While open, the flower was exposed to an average maximum daily temperature of 31.8C and minimum of 18.7C but of course, it had been pollinated which could lead to premature aging. A third flower bud appeared in early July but the developing fruit was still hidden by bracts. This third and last flower opened on July 17 or one month after the first. It was smaller and lasted only two days. It was exposed to an average maximum of 29.3C and minimum of 22C while open. My experience is limited to these three blooms but flower aging could be affected by temperature, something that I intend to followup next year. The fruit began elongating rapidly from 10 days after pollination. On July 20 (24 days post-pollination) the fruit was 90 mm long. Increase in girth ceased for about a week in early August which in my experience is the interval when fertilization is happening. This was 40 to 50 days post pollination. After fertilization, capsule growth resumes and will continue until the seeds are matured. According to my 1990 notes, this should be when the fruit reaches 25 mm diameter. Once the seeds are ready, I will sow them on a range of media containing charcoal. Knowing that the seeds are short-lived, I plan to have replicates so that all germination stages can be photographed. Sobralia xantholeuca is a desirable showy species that is relatively easy to grow. It prefers an open mix of bark/coconut chips and humus or compost. Watering is a daily requirement as is weekly feeding year round. The plants tolerate a range of light and temperature conditions but seem to thrive in summer heat and humidity. It is possible that cool nights induce flowering in early summer. The specific epithet was published in 1885 but it was clearly known in cultivation before then. There are 11 registered hybrids, the first being Sob. Wiganiae (1856) and the most recent, Sob. Songbird (2004). Various sources tell us that fruits dehisce at 68 days to 8-10 months post-pollination. I look forward to reporting the capsule age at dehiscence but suspect that it will be less than 100 days. SPIRANTHES Have you ever wondered what it would be like to have wild orchids pop up in your garden or greenhouse? I have had reed stem Epidendrums germinate in a shadehouse and Spathoglottis germinate in pots of other plants but these were all plants in cultivation. Imagine my surprise when in 2003, I found a tiny leafy rosette of what I assumed was a Spiranthes growing in a pot of aloes placed in my summer garden. I found another similar rosette in a pot of Cinnamon Yam nearby. The one thing in common was that the potting material, a commercial peat-perlite preparation. Where had the seeds come from? A peat bog was a possibility or maybe they had blown in. I had to shelter the Aloes pot from frost but the yam seedlings needed a cold rest. That pot was stored over winter in an unheated garage where the temperature dropped to -10C (14F). The aloes pot was stored in a cool room at 5 to 10C (41 to 50F). The Spiranthes in the cool room did not survive but the seedling stored cold in the garage survived with just the leaf tips dried. When the weather warmed, I placed this pot outdoors and watered it. Within a few days, the leaves began to expand and new leaves appeared. This rosette enlarged until some leaves began to lengthen. A flower spike emerged and flowers opened in August. It was Autumn Ladies Tresses, Spiranthes cernua. Fruits formed and many seeds were produced. I prepared seed packets to test germination in other potting mixes. The few seeds left were scattered over the pot surface near the mother plant. Eventually, the pot was placed in the garage to overwinter. In spring 2005, two shoots emerged near the base of the old plant and three offsets appeared around the edge of the pot. Additionally, six tiny seedlings appeared where I had scattered seeds. That these were seedlings and not offsets was proven by carefully lifting the soil beneath the plants. Offsets have an obvious stolon connection. Seeds had germinated in the various packets but remain protocorms beneath the soil surface. What is most exciting is finding a new seedling in yet another garden pot prepared from the same batch of peat mix. I wonder how long orchid seeds can remain viable in the peat mix? This year's inflorescence had over 25 flowers and thus will provide many 'volunteers' with which to experiment. I am looking forward to learning about yet another facet of orchid life. |
