A host of golden daffodils has sprung to life, bringing a blaze of colour to many of York's historic sites.

But though the embankments of the city walls shimmer under a sea of sunshine yellow, the grassy base of Clifford's Tower stands unusually bare - possibly due to global warming.

For those accustomed to seeing spring in all its glory at the foot of the monument, the mound appears almost naked, with barely a pretty petal in sight.

Susan Sadler, site supervisor at Clifford's Tower, said of the daffodil vanishing act: "They have come and gone."

The disappearance is quite remarkable, considering the hundreds of thousands of bulbs planted in the tower's shadow in the early 1990s.

School children and members of the Army undertook the mammoth task on behalf of an American Jewish Society in memory of those who died in a massacre 815 years ago.

The tower's high mound - created by William the Conqueror as part of his bid to dominate the north - was the setting of one of the most terrifying events in York's history.

In 1190 Jews sought refuge inside a wooden keep atop the mound while under attack by a local mob. Rather than fall victim to the violence of their assailants, many of the Jews committed suicide and set the keep on fire. When the survivors emerged the next day, they were massacred.

Susan said the Clifford Tower daffodils were an early-flowering variety because of the number of petals.

"It is a six-pointed variety like the Star Of David. They also picked a variety that would flower usually around mid-March - March 16 is the anniversary date - but they have flowered earlier than normal this year, probably because of global warming."

Observers will have noted that the flowers started to peep through as early as the end of January before opening up from mid-February.

"They were all out on March 16, but they had been out for a while. A few years ago they would just be coming out then," she said.

"I am in my eighth year here and they are definitely flowering earlier. In this last week they have all gone brown and look awful."

Sadly, many of the 250,000 bulbs have been damaged by people clambering on to the slopes.

"A lot have been vandalised," said Susan.

Speculating about the lack of daffodils at Clifford's Tower, Evening Press gardening writer Gina Parkinson said the previous year's weather played a big role in how the bulb flowers again.

"It may have been very dry last April and May and we also had a very dry spring in 2003," she said.

Updated: 10:05 Tuesday, April 05, 2005