I heard that the largest INFLORESCENCE is an arum several feet long, made up of lots of small tiny flowers, and it resembles a calla lily jack in the pulpit type thing. But what is the largest individual FLOWER? And if it is Rafflesia arnoldii, where do they grow? Can I send away for one? I can’t find any in various catalogues. Finally, this parasitic plant is said to consist only of a huge flower, is this true? Not even a root to get water?
I had thought that the Amorphophallus titanum was the largest flower. It is stated as such here: http://www.huntington.org/BotanicalDiv/TitanIntro.htm
Here’s a good page on Rafflesia: http://bengkulu.wasantara.net.id/yahoo/wisata/bunga.html
According to my copy of the Guiness Book of Records, Rafflesia arnoldii, the parasitic stinking corpse lily of Southeast Asia, has the largest single bloom, being 3 feet in diameter.
The largest inflorescence is that of the rare Bolivian Puya raimondii, 8 feet in diameter with 8,000 individual blooms.
Aaah yes, but Amorphophallus is an inflorescence, or compound flower. Probably the first ‘flower’ the OP referred to.
According to this, Rafflesia arnoldii is the largest bloom, up to 3 feet across. It has only been grown in one botanical lab in Indonesia, so I don’t think you can get one. 
It’s interesting that it and related plants get pollinated by emitting the odor of rotting flesh, thereby attracting carrion flies.
There was an article in Science News about Rafflesia in 1999. I believe it said they were the largest flower. And IIRC, they are native to Southeast Asia, specifically Malaysia. And yes, they are basically all flower, with just enough plant to attach them to a tree.
Unfortunately, the Science News article is not on-line, but here’s a link to its references.
OK, it seems I’m following bibliophage around and simulposting. I am not a stalker. Honest!
Apologies… my bad. Read deeper into the article and realized it was an inflorescence. The Huntington Botanical Gardens are attempting to cultivate the Rafflesia here in California. Doubt you could get hold of some seeds though.
Rafflesia arnoldii is a stem parasite in vines of the genus Tetrastigma. It grows totally within the vine, and you would not see it unless you saw evidence of a flower, or the flower itself. The plant produces about 4 million seets, which, if they land in a moist crevice on a Tetrastigma vine, it germinates, and the plant sends out a network of cells much like a fungus. Eventually when it does flower, it pushes the bug out through the bark, and expands into a huge flower, about 3 feet across. The flower smells like rotting flesh (and the appearance is similar), which attracts carrion beetles which pollinate the flower.
There’s a minute relative in the Anza Borrego desert of California. It’s called Pilostyles. The flowers are very small, and the plant inhabits dyeweed plants (Psorothamnus emoryi).
The largest inflorescence however belongs to Corypha umbraculifera or, the Talipot Palm. The tree lives its life for only one thing - to flower. When it does flower, it uses up so much of its energy in producing the massive inflorescence, that it dies. Here is an image Talipot Palm
Whoops. That should be bud, not bug.
The Kew Gardens website http://www.rbgkew.org.uk/kewscientist/ks_oct96/titan.html has stuff on *Amorphophallus titanum *
being a naturalist, I would like to remind all that a flower is the sex organ of the plant.
At any rate from the Worlds Record book, might be a little old:
The largest of all blooms are the parasitic stinking corpse lily (Rafflesia arnoldii). They attach
themselves to the cissus vines of the jungle in southeast Asia and measure up to 91 cm 3 ft across
and 1.9 cm 3/4 in thick, and attain a weight of 7 kg 15 lb. True to name, the plant is extremely
offensive in scent. Inflorescence The largest-known inflorescence as distinct from the largest of all
blooms is that of Puya raimondii, a rare Bolivian monocarpic member of the Bromeliaceae family with
an erect panicle (diameter 2.4 m 8 ft) that emerges to a height of 10.7 m 35 ft. Each of these bears up
to 8,000 white blooms (see also Slowest flowering plant). The flower-spike of an agave was in 1974
measured to be 15.8 m 52 ft long in Berkeley, CA. Blossoming plant The giant Chinese wisteria
(Wisteria sinensis) at Sierra Madre, CA was planted in 1892 and now has branches 152 m 500 ft
long. It covers nearly an acre, weighs 228 tonnes 225 tons248 tons and has an estimated 1.5 million
blossoms during its blossoming period of five weeks, when up to 30,000 people pay admission to visit
it.
I just have to say, that this is the longest post I’ve ever seen handy produce. Wow.