Ecology of the Barnacle Goose Tree

Medieval writers believed in the strangest things. Once upon a time people believed that barnacles grew from trees and hatched into geese. In fantasy land, this is true!

The barnacle goose does not lay and hatch eggs in the manner of other birds. The barnacle geese drop their eggs in the sea, the waves churn them into froth, and the barnacles that result will cling to any available surface such as ships and driftwood. Embryonic geese gestate within the barnacles, then eventually hatch and fly away to repeat the cycle.

It is unclear where the famous barnacle goose tree fits into this life cycle. The tree grows in or near the sea, or on driftwood like seaweed. It grows barnacles like other plants would grow fruit, eventually producing geese.

Explanations:

• The barnacle tree does not exist. Agglomeration of barnacles on large driftwood were mistaken for trees and the rumor grew out of control.
• The barnacle tree is a different species that lives in symbiosis with the barnacle geese, cultivating barnacles on behalf of the geese in exchange for an unspecified benefit.
• Barnacles reproduce asexually in the manner of the polyp. Barnacles grow into barnacle trees, which bud yet more barnacles. At some point, certain barnacles will change and develop into geese instead. The adult geese will mate and spread the froth that becomes more barnacles.
• The stages of the barnacle goose tree do not form a life cycle, but are spontaneously generated in the same manner as rotten meat produces maggots and leftover grain produces mice.
• There are many different species of barnacle geese which alternate between different generations. Some alternate between geese and barnacles, geese and trees, or all three!

Relevant links:

• http://bestiary.ca/beasts/beast1195.htm
• http://davidmcraney.com/goose-trees/
• http://scienceblogs.com/evolvingthoughts/2006/08/15/tales-of-the-barnacle-goose/
• http://www.dailymail.co.uk/news/article-2050590/The-barnacle-sea-monster-Everglades-tree-trunk-covered-weeds-creatures-washed-Devon-beach-uprooted-Hurricane-Katia.html
• https://sercblog.si.edu/?p=3069
• https://www.canterbury-cathedral.org/heritage/archives/picture-this/the-strange-case-of-the-barnacle-goose/
• https://www.wired.com/2008/07/geese-from-barnacles/
• https://en.wikipedia.org/wiki/Barnacle_goose#Folklore
• http://www.medieval-baltic.us/barometz.pdf