These two sound quite similar. Maybe swap one of these out, for the sake of diversity? Of the two, I like the Carapace least - sounds more like a disease (e.g. Lycanthropy) than an actual plant. We never see its plant form, it doesn't behave like a plant, it doesn't look like a plant...BOZ said:4. Underdark Plant Creatures
These fungi, molds, and other plant creatures are all found in subterranean realms, waiting to devour anything venturing into the depths.
Carapace (CR 1/4)
This aggressive, symbiotic fungus infests vertebrate creatures, and hardening their skin to make a sort of exoskeletal shell. The creature eventually takes over its host's mind, by replacing spinal and brain tissue with its own fungal matter.
Originally found in Dragon #227/Monstrous Compendium Annual 4.
Zygom
The mushroom caps of this fungoid growth contain a highly adhesive glue that spills out when broken. This substance contains spores that infest a living creature, allowing the fungus to take control.
Originally found in Monster Manual II.
Edible to humans? I.e. underground explorers would simply take a long some tinder and some Fireweed instead of rations?Fireweed: underground heat-absorbing plant, immune to fire, converts heat into edible vegetable matter (Dragon #227)
Note that Brown and Yellow Mold (along with Green Slime and Phosphorescent Fungus) are already part of the SRD - no need to reprint those. (In the "Wilderness, Weather, and Environment" section. They were accidentally left out of the SRD originally, but were added back in later.)Brown Mold: feeds on heat, killing creatures by draining the body heat out of them (Monster Manual, 1977).
Yellow Mold: emits a deadly spore cloud, can use suggestion 2/day and drains Intelligence (Monster Manual, 1977).
BOZ said:5. Plant creatures
These plant creatures didn't really seem to me to fit into any of the above categories, but there are some really cool critters in here. The theme? They are all plants! Who needs more than that (see article in Dragon #292)? Some of this variety is malevolent, some benevolent.
Too much overlap with Carapace/Zygom?BOZ said:Dusanu (CR 5)
This creature looks like an undead at first glance, but is actually a strange mold that animates and controls a skeleton. The rot fiend's fungus is released in a spore cloud, and changes a victim into a new dusanu.
Originally found in D&D Setting/Mystara.
Now *those* are cool! Could we upgrade these from "alternate" status, pretty please? They're quite different from most of the other plant we have in there, and very flavorful. *Much* better than "yet another plant critter that tries to kill and eat you"...Faerie Phiz: fey-like face appearing on enchanted wood, spit extinguishes flame and irritates skin, casts spells as both wizard and druid, has sagelike knowledge (Dragon #191)
Oblivax: memory moss is a black moss that steals memories from intelligent creatures, as well as prepared spells from spellcasters. eating the moss gives these stolen properties to a creature. (Monster Manual II)

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.