In the Araceae family, this aquatic plant grows spathes like other members of the family; see
http://phytoimages.siu.edu/imgs/paraman1/r/Araceae_Pistia_stratiotes_15121.html
I had to flash this shot because none of the white balance settings seemed to correct for the artificial lighting in the greenhouse. I want to ask Rich about the lamps he uses in the winter to extend our short winter days for the plants accustomed to longer days in their natural habitats (metal halide? high-intensity discharge?).
As for this plant, there's an amusing write-up at the Floridata Plant Encyclopedia,
http://floridata.com/Plants/Araceae/Pistia%20stratiotes/559 » “Waterlettuce is a floating water plant with 6 in (15 cm) rosettes of ribbed, Ruffles® Potato Chip-like leaves. The rosettes are connected by stolons that break easily. The leaves are fleshy-thick, pale green and velvety-hairy, which causes water to bead and keeps them from getting wet. The feathery roots are white, purple and black, and quite showy, hanging down a foot or so below the floating rosettes. Waterlettuce frequently forms solid mats on the water's surface and can become a serious pest.
“Waterlettuce thrives in still waters in swamps, ponds, lakes, and sluggish rivers in the tropics and subtropics in both the Old and New Worlds. In the United States it is restricted to Peninsular Florida where it probably was introduced.
“Culture
Light: Waterlettuce needs full sunlight or slightly filtered sunlight.
Moisture: Waterlettuce typically floats on the surface, but can withstand periods of drawdown as long as the mud does not dry out completely.
Hardiness: USDA Zones 10 - 11. Occasional in northern Florida, Zone 9.
Propagation: Waterlettuce propagates vegetatively by growing stolons (stemlike shoots) which produce new rosettes. Seeds are produced in the tropics and these are said to be easy to germinate. Waterlettuce apparently does not flower in Florida, perhaps because an essential pollinator is not present.
“… Waterlettuce is on the Florida Department of Environmental Protection's list of Prohibited Species, and as such it is unlawful to possess or transport this plant in Florida.
“As pretty and interesting as it is, waterlettuce is a huge pest and is prohibited by the Florida Department of Environmental Protection. Culture of this aquatic is probably better left to aquarium enthusiasts - indoors (but nowhere in Zones 8-11)!
“… This noxious pest is able to completely clog waterways and eradication is difficult and expensive.”
Several other states classify P. stratiotes as "noxious," "invasive" or "prohibited":
http://plants.usda.gov/core/profile?symbol=PIST2
Species page at PhytoImages,
http://phytoimages.siu.edu/cgi-bin/dol/dol_terminal.pl?taxon_name=Pistia_stratiotes&rank=binomial
Photo taken at SIUC Plant Biology Greenhouse,
http://www.plantbiology.siu.edu/facilities/plant-biology-facilities/greenhouse/index.php
1 year ago (“Lipstick plant”):
http://365project.org/rhoing/365/2015-01-15
2 years ago (“Five years later: Much more intricate!”):
http://365project.org/rhoing/365/2014-01-15
3 years ago (“Pseudogynoxys cummingii”):
http://365project.org/rhoing/365/2013-01-15
4 years ago (“Blue (or ‘Touchdown!’?”):
http://365project.org/rhoing/365/2012-01-15
5 years ago (“Snow routes”):
http://365project.org/rhoing/365/2011-01-15
[ IMG_8502S12x8Utm :: f/5 :: 1/60" :: ISO-400 :: 60mm :: flash ]
![Sigh. [Travel-day]](https://media.365project.org/1/9428160_bfilmqru48_sq.jpg "Sigh. [Travel-day]")