Brambles are missing

Brambles spontaneously spawned in my game after tinkering with my customization settings. I was experimenting with the weather mechanics and I wanted to observe the various seasonal effects that had been implemented alongside the Hamlet expansion. They appeared in mass after I altered the default season from 'Temperate' to 'Humid'. They behave similarly to lure plants in that they are an invasive plant species. Like the lure plants, they also appear to be a seasonal spawn. 

I've included a screenshot that I captured earlier today, within the 'Spoiler' tag, below. 

Spoiler