Industry bodies are working to get plant identification put back on the City & Guilds curriculum after being surprised at its removal.
Recognition of key plants was a core skill needed to pass production horticulture and parks, gardens and green spaces level two City & Guilds diplomas but was made optional in both from 1 January.
It remains mandatory for City & Guilds horticulture level two. BALI and the HTA are unimpressed and said their members agree.
Chief operations officer Wayne Grills said: "This is a step in the wrong direction when plant identification is such a key skill.
"We are working hard to demonstrate that this sector has a competent and skilled workforce and this apparent deskilling will not sit well with the industry."
Grills said recent EU and UK legislation on invasive plants and health issues with some species made it even more important for everyone in the industry to be able to identify friend from foe when at work.
A City & Guilds spokeswoman said the decision was made because sector skills body Lantra decided that it should not be a mandatory course. It had to comply to remain eligible qualifications for apprenticeships, she pointed out.
Boningale chairman Tim Edwards said he was not aware of the change and was not consulted. "It does seem a bit bonkers," he added.
"I would have thought anyone going into production horticulture needs to be able to do basic plant identification. I can understand landscape contractors not needing to know it if they use plants identified on delivery but in a nursery situation you expect your staff to know what they are looking at."
But David Winn at Lantra said the industry requested the change. "We had a review of employers at least 18 months ago. We have to do this every three years.
"People in production horticulture didn't want it because they're producing very few varieties.
"The greenkeepers and sports turf people said they deal with several grasses but don't need to know everything else. Contractors and some parks people said they'd rather it was an option.
"Eighty people from across the sector and the UK were consulted. I think it's a very sensible decision."
"I am disappointed. This was a surprise to us. We are concerned - horticulture skills are ever decreasing in the industry"
Penny Evans, training and careers manager, HTA