Ivy?

That was inadvertant elm, I got confused there for a minute.

Looks like Red Dwarf were cribbing from a botany textbook there. Their computer being called Holly & the episode with the polymorph

I can see the connection. Polymorphism is a change of leaf shape exhibited by Holly & Ivy. In the case of Holly, it doesn't need to put energy into producing spikes when the plant has got above grazing height, so the upper leaves of a Holly are often smooth. Not quite sure why Ivy does it though.

Anyone remember Douglas Adams Hitch Hikers Guide with the bit about Ford Prefect being the only survivor of the Great Colapsing "Hurung" disaster ?

The dictionary defines a Hurung as a ford marked by a pole. One of those measures that tells you how deep a flood is.

I wonder if there was inspiration in the authors mind from that, we'll sadly never know now.