Inflorescence Odor Changes in Response to Temperature

From: Don Burns <burns at mobot.org> on 1997.12.16 at 03:15:42(1758) The temperature is again tonight dropping into the low 50degF point and it is very windy. Since the wind chill will probably put the effective temperature far below 50, once again the water dwellers will spend their night in the garage. The Uropspathas have a number of inflorescences most of which this afternoon were exuding their characteristicly sweet melon-like odor. Just a few hours later, the fragrance is gone. I know this is not a response to darkness, as they were quite fragrant last night at 11PM. The sole other significant change that took place in the past few hours is the temperature: It has dropped at least 12 or 13 degF. Has anyone else observed odor changes in response temperature changes? Granted, this is certainly no controlled experiment I have just performed, but I do intend to check out what these guys smell like again mid-day tomorrow. I am aware of plants whose flowers respond to light, or lack of it, to raise the intensity of flower odors, my favorite being Brassavola nodosa, the orchid that is pollinated by specific night flying insects. But I have not night heard of plants with flowers that respond to temperature. Don +More Don Burns Plantation, FL USA Zone 10b

From: Lester Kallus <lkallus at earthlink.net> on 1997.12.16 at 13:56:33(1759) I don't know if it's defiinitely a response to temperature but Brugmansia is distinctly different when the weather cools. On warm evenings with temperatures above 70 (just a dwindling memory for me now that there's ice outside) my Brugmansia can be detected from the opposite end of the yard. On cooler evenings with temperatures in the 50s, you have to stick your nose directly into the Brugmansia to notice that it is fragrant. I know that it's also a change in the season, but if there's a surprise warm evening, the Brugmansia suddenly becomes fragrant again. Les

From: "Julius Boos" <ju-bo at classic.msn.com> on 1997.12.16 at 14:11:08(1762) ---------- Sent: Monday, December 15, 1997 10:15 PM To: ju-bo@msn.com +More Subject: Inflorescence Odor Changes in Response to Temperature >>The temperature is again tonight dropping into the low 50degF point and it is very windy. Since the wind chill will probably put the effective temperature far below 50, once again the water dwellers will spend their night in the garage. The Uropspathas have a number of inflorescences most of which this afternoon were exuding their characteristicly sweet melon-like odor. Just a few hours later, the fragrance is gone. I know this is not a response to darkness, as they were quite fragrant last night at 11PM. The sole other significant change that took place in the past few hours is the temperature: It has dropped at least 12 or 13 degF. Has anyone else observed odor changes in response temperature changes? Granted, this is certainly no controlled experiment I have just performed, but I do intend to check out what these guys smell like again mid-day tomorrow. I am aware of plants whose flowers respond to light, or lack of it, to raise the intensity of flower odors, my favorite being Brassavola nodosa, the orchid that is pollinated by specific night flying insects. But I have not night heard of plants with flowers that respond to temperature. Don<< Dear Don, This is interesting on two points, the first being that I have only noticed odur being produced by my Urospathas around late mid-morning to mid-afternoon, and always assumed that it was triggered by the warmth. My plants took a hit from the first cold snap earlier, so none have infloresences that I can check now. The second point is odor perception in these plants. The Urospatha sp. I have from the Orinoco Delta, Venez. (that I used to believe may have been U. sagittifolia, now I await further research), produces an odor that to me smells of rich, mixed fruit salad, but a LITTLE "past the prime" (stale), whereas the U. grandis from Tortuguero Canal in Costa Rica, when I first smelt them, evoked OLD childhood memories of walking under a mango tree AFTER the fruiting season, when the old, dry remains of fruit and skins are on the ground. It was only after a visiting friend smelt this plant`s bloom and he suggested "cantelope !" that it registered in my consciousness that it also evoked this relatively unfamiliar (to me !) odor. If possible, ask visitors or your wife to test the odor and tell you what it smells like to them. I have not smelt lemon in my blooms, but lemon (the lemon of temperate climes) is not an odor that I can or would be able to "pull up" from my memory bank, as being from the tropics, our lemons smell very differently ! Which Urospatha was in bloom, the U. grandis or the one with velvety leaves from Fr. Guiana ? I do not remember what that one smelt like, but know that it smelt differently to the others in my collection, as did one I lost (with angular petioles) from El Tigre in E. Venez. All very interesting ! Cheers, Julius ju-bo@msn.com Don Burns Plantation, FL USA Zone 10b

From: Rand Nicholson <writserv at nbnet.nb.ca> on 1997.12.16 at 14:15:12(1763) >The temperature is again tonight dropping into the low 50degF point and >it is very windy. Since the wind chill will probably put the effective >temperature far below 50, once again the water dwellers will spend their >night in the garage. The Uropspathas have a number of inflorescences most >of which this afternoon were exuding their characteristicly sweet >melon-like odor. Just a few hours later, the fragrance is gone. I know >this is not a response to darkness, as they were quite fragrant last >night at 11PM. (Snip) >But I have not night heard of plants with flowers that respond to >temperature. > >Don It would make sense that plants that produce volatile oils and such to produce an odour to attract pollinators would shut down below a certain temperature. Most insects also shut down and become torpid at lower temperatures, also. Kind Regards, Rand (-18 C) +More Rand Nicholson New Brunswick Maritime Canada, Z 5b

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