Royal Botanic Gardens, Kew staff have learnt the breakdown of which departments' jobs are under threat, following last month's announcement of 125 redundancies.
Most of the roles to go are in the sciences, with 40-50 set to leave. From public programmes 35-45 jobs are threatened, from corporate services 25-30, plus fewer than five each from horticulture and Wakehurst Place.
A restructuring process is to complete in mid July, when Kew management will launch a formal consultation process lasting 90 days.
Prospect union officer Julie Flanagan, who started a Change.org website petition calling for central Government to reverse the funding cuts that have partly led to the Kew's £5m budget shortfall, said: "I think in reality the staff knew that something like this was coming. They did know there was a hole in the budget. The biggest shock is that the majority are in the science area."
She added that Kew is running the latest in a series of voluntary exit schemes but only around 30 people have expressed an interest so far, which would still leave an estimated 95 staff members facing redundancy.
"We've no idea of the numbers who might want to go. I don't think there will be enough to avoid redundancy for some who don't want it."
Since Whitehall set Kew adrift in 1983, making it an executive non-departmental public body, Government funding has dropped from 90 to 40 per cent of the operating budget, said Flanagan.
Number of signatures to date on Change.org petition to reverse Government funding cuts - early day motion signed by nine MPs - 78,514 signatures.