Mystery surrounds the death of a gardener from Hampshire who died days after brushing against a highly-poisonous plant, an inquest heard today.

Nathan Greenway was experienced at looking after the gardens at the sprawling mansion he was working at, but collapsed hours after brushing against the deadly flower aconitum - also known as Devil's Helmet and Monkshood - growing in the grounds at Christopher and Katherine Ogilvie-Thompson's home.

The 33-year-old was clearing up in the garden ready for a party when it is believed he brushed against the plant while clearing weeds. Hours later, he suffered sickness and diarrhoea.

Doctors were initially worried he was suffering from ebola after he arrived at hospital, where he died days later.

Reliving the day he began to suffer symptoms, his widow Tegan Greenway said he returned home and went to bed.

She told the inquest: "I slept in the spare room because I didn't want to catch the virus.

"When I woke up, I realised he wasn't in the bedroom. I went downstairs and found him collapsed on the floor in the living room.

"He was drenched in sweat, there was an imprint on the floor."

Mrs Greenway called her husband's father Richard and he was taken to hospital. However, he suffered multiple organ failure and died.

The widow, who met her husband in 2007, told the inquest in Basingstoke, "He had lacerations on his hands. Nathan was never one to complain but he said he felt as weak as kitten. He said he was starting to fear he would not make it."

She added: "Nathan could not even stand. The paramedics said he was just dehydrated but on the way to the hospital, a call was made saying we were going in as an emergency case. He was going a shade of blue. They were worried about ebola. I was told his organs were failing."

Her husband, aged 33 years, was employed by South African-born Mr Christopher Ogilvie-Thompson and his wife Kathy to maintain the manicured gardens of their sprawling estate in exclusive Upper Froyle near Alton, Hants.

Head gardener David Edwards told the inquest that Nathan had begun working there in 2012.

He said: "I saw him every day. We had a large party coming up in September so we were getting the garden ready. We were working our way around the garden, weeding and edging flower beds.

"I was not aware of the dangers of Monkshood. My wife Caroline is a florist and she had worked with it before, I would not have thought Nathan would have recognised it.

"He was not wearing gloves. Gloves were available, but he did not like wearing them.

"He had his own set of gloves in his car."

The gardener's father, Richard, told the inquest that his son told him he was "really worried" before he was taken to hospital. He added: "That told me he had symptoms he had not experienced before as he was usually dismissive of illness. We all felt he was slipping away."

The inquest heard the plant, a member of the buttercup family of ranunculaceae, had been in the garden for around 35 years and at least 15 people had worked on the estate in that time.

Millionaire Mr Ogilvie Thompson, a consultant for high-end technology companies, lives with his wife in the Grade II listed Georgian house in Upper Froyle near Alton in Hampshire. They listened to proceedings intently.

Pathologist Dr Deborah Cook said: "This is obviously a very tragic but extremely rare death. He was unwell for 29 hours before he was taken to hospital.

"The symptoms sounded like a winter flu bug. This is a popular garden plant and there are not a large number of people coming to hospital with aconite poisoning.

"The illness was triggered by exposure to some toxin, some virus or fungus, there was very rapid deterioration of irreversible kidney and liver failure.

"The primary cause of death was multiple organ failure. I am unable to say aconite poisoning was more likely than not the underlying trigger for death.

"The symptoms are not specific as to the cause."

Mr Greenway, of Aldershot, died at Frimley Park Hospital on September 7 last year, days after falling ill.

Sedation was withdrawn the previous day, when his skin began to peel away.

Devil's Helmet Credit: John Robertson

North Hampshire coroner Andrew Bradley recorded an open verdict and said: "When I first picked up this case, I was under the impression Nathan had handled it.

"He did not actually handle the plant. In my view, it is not sufficient to find aconite poisoning.

"Something happened with Nathan on August 27. He developed a catastrophic condition and was taken by ambulance to hospital.

"His kidneys failed and he was on a downwards slope. It is the unknown that leaves us in this quandary.

"I like to have answers to questions. I can tell you how he died but not why. It is clear he developed a catastrophic illness.

"The cause of death is multiple organ failure of unknown cause. That does not explain anything."

In a statement released after the inquest on Mr Greenway, Christopher and Kathy Ogilvie Thompson said: "We were all very shocked and deeply saddened at Nathan's extremely sudden and tragic death.

"He had worked at Mill Court for more than two years. As part of the team he made an important and valued contribution to the maintenance and development of the gardens.

"We know his family were all devastated at his loss and both they and Nathan remain in our thoughts and prayers."