A contractor chopped down 19 protected trees including a rare Plymouth Pear, a court heard.
Plymouth magistrates were told that Christopher Seymour felled the Plymouth Pear tree – one of only around 20 growing wild in the city.
The 47-year-old was fined and ordered to pay costs totalling £2,765 for what his solicitor called a "very unfortunate error".
The court heard Plymouth Pears only grow in the city and around Truro and have unique legal protection.
Helen Morris, prosecuting for Plymouth City Council, said the first specimen was identified in the city and it was "emblematic" of it.
Seymour, of Southway, Plymouth, admitted six offences of contravening tree preservation orders by cutting down trees and asked for 13 similar offences to be taken into consideration.
Together with the Plymouth Pear, he felled an oak, an ash and several holly trees.
Mrs Morris said Seymour, trading as Plant Tech, chopped down 19 trees at the Cannon Mill industrial estate in Estover Road on April 4 or 5 last year.
She said members of the public called the council and the tree officer contacted Seymour and stopped him chopping down any more trees – but half the group were gone.
Mrs Morris added the trees, some 40ft high and up to a 100 years old, were given protection orders in 1990.
She said the rare pear tree was found in Plymouth by local naturalist Archer Briggs in 1870.
The court heard it is the only tree species given special protection under Schedule 8 of the Wildlife and Countryside Act 1981, which was designed to protect especially rare species in England and Wales.
Mrs Morris said Seymour told the council he had been told by landowners London and Westcountry Estates to tidy up the site for a prospective tenant. But he was not specifically told to fell the protected trees.
Patrick Somerville, defending, said: "This a very unfortunate error for which he is deeply remorseful.
"The area was not very well maintained, overgrown and a bit of a mess and frankly he never would have known in a million years that the trees were protected."
He said Seymour had offered to replant the felled trees at a cost of about £1,300.
Magistrates fined him £1,000 for felling the Plymouth pear and £250 for each of the five trees named in the charges. He must also pay costs of £500 and a victim surcharge of £15.