volunteer with huge exotic flower

I found this plant weeks ago, in a garden I tend at work, and left it to reveal itself to me over time. Last week I noticed a very large, long, rolled aubergine coloured 'flower' or spathe ? with a darker coloured spadix ?
The leaves are large bright green and smooth with multiple divisions; the stem is thick, strong and variegated in colour; the base of the flower is bulbous. Is this perhaps a Calla of sorts? Can it reproduce itself ? When I go to dig it up to relocate it, what am I looking for at the base beneath the soil so I do not damage anything, yet get it all?
Many thanks for the assistance.

 

Dracunculus vulgaris.
Dracunculus vulgaris - Plant Finder

I think they're something people are pleased to have. @pmurphy posted hers in the thread at Virtual Garden Tour
I think they're very cool and photograph every one I find, have been following the ones I know of in Stanley Park, which have been planted by the gardeners.

I don't know when it's supposed to smell - maybe when the spathe opens? The spathe on the one that has finished blooming near the Stanley Park Pavilion just shriveled up and didnt' open.

 

Smell is strongest when it first opens and the flower only lasts about a week.
I would mark the position of the plant now and then when relocating, look for a large bulb.

 

...ever learning. Do you know, if over time they 'spread' to have multiple spathes, similar to cala lilies, and/or create multiple 'bulbs' like crocosmia or bluebells? Thank you.

 

One bulb, one plant, one spathe.
If you're lucky enough that the flower has been pollinated you may get more but it will take years; they will not spread like bluebells.
The plant will also get very large - my largest (this year) was well over 1 meter tall.

 

Christopher Lloyd wrote about using this species as a cut flower because of the odor disappearing while the inflorescence still had days of life left in it. However when the odor is still present it smells quite like a dead rat, and can be detected from some distance. In Seattle dragon arum is fairly prevalent as a surprise feature coming with recently purchased residential lots, as though it has a history of being passed around. Or maybe it has been persisting and dispersing on its own - multiple examples being present on any given site is not unusual.

When the proportionately large fruits are produced these are a feature in their own right, looking as they do like fluorescent orange corn cobs when mature.

 

Thank you all for your insights and experiences.

 

As Ron mentioned Christopher Lloyd or Christo as he was affectionately known.
Can I reccomend this book by him, it's a lovely read.
Brings you into his garden of Great Dixter if you have never had the chance to visit.
We did about 15 years ago now and loved it.
Exotic Planting For Adventurous Gardeners