Sydney rain leaves goop on footpaths caused by sap from flame trees

A mystery substance has been plaguing pedestrians after appearing on footpaths throughout Sydney. 

A picture of the strange gel-like substance was posted to social media on Thursday. 

‘Does anybody know what these transparent goopy things are?’ the caption read.

The recent weather and native Australian flame trees are behind this footpath-phenomena

And while many were just as confused by the goop, others explained how there was a very simple explanation. 

‘Looks like sap from flame trees. Usually happens when it rains. The black things to the side look like flame tree pods,’ one person wrote.

A high pressure system off New Zealand has caused non-stop rain across Australia’s east coast over the past week, which is expected to continue into next week.

Brett Summerell is the Chief Botanist with the Australian Institute of Botanical Science, he told Daily Mail Australia that the tree’s mucilage is usually produced by flame trees as a reaction to insect activity or cuts on the tree.

‘But what we’re seeing at the moment with the rain that won’t stop is that the trees are taking up so much water they’ve got to flush a lot of it back out of their systems leaving the sappy mixture below them,’ he said.

The mucilage-water substance looks like spilled glue or the clear jellyfish that sometimes wash up on beaches.

The illawrra flame trees typically flower once every five years in an incredible display after they rid themselves of their leaves

The sappy mixture is quite caustic and can cause damage if left atop an unfortunately-parked car. 

Like Jacarandas, flame trees can flower on bare branches, but only occasionally – every five years. 

At this time of year, most trees feature claw-shaped leaves and seed pods if they’ve flowered.