Glow Berries "plant" can appear on the ground without the column of its plant above it

When I created a unique biome world, with Lush Caves as the biome, I started exploring the world and I found a glow berry plant with glow berries on the ground and it didn't have its glow berries plant above it. The specific name of that block is "minecraft:cave_vines_head".

 

You can check it in a Lush Caves' unique biome world in coordinates 21 -7 -185 on the seed 3612714367576485365.