How can living plants be used militaristically? [closed]

Question

To be clear, we're talking about any organism found on earth that's classified under the kingdom Plantae. Assume these plants won't be genetically modified at all when they're used in the military and that the army's composition is 85% human and 15% plant.

I'm not asking for specific plants to use (although that would be helpful to include in your answer), but rather, how living plants could be used in warfare in the first place. The usage of the plants can also be indirectly impactful; for example, planting tall trees and annoying vines in a buffer zone between two military camps can act as an obstruction for an opposing army trying to invade. So far, however, that's the only idea I've thought of. How could plants be used in an army?

Answer 1

The biggest usage of plants in real world military is supportive:

• Camouflage
• Food for living parts of army
• Source of material (for example easy gettable wood for buildings or for low-tech weapons directly; or fuel)
• Physic obstacle - live fences, cacti fences, or just dense vegetation formation

However you can use plants for some direct attacks, there you want to exploit destructivity of plant life. For example roots going inside mini holes in concrete, making them bigger until concrete gradually loses its initial character of solid wall.

Also some plants can be spread airborn, can grow up fast and then spread more seeds, potentially harmful ones (Spores that can "attack" other living beings, like fungi, molds - even though they are not technically exactly Plantae).

• Meat-eating plants for traps or direct attack (if you can find plants big enough, for example triffids)
• Plants that release some spores or dangerous gases, toxins...
• Plants that physically deteriorate enemy bunkers by invasive growing
• Parasite plants that attack enemy strategic plants (for example spoiling wheat, but again, that is more common for fungi/molds)

The problem with direct plant usage is the time scale of such an action, where it usually takes a lot of time. However in wild nature, most of those processes is natural, put a city somewhere and wait - plants will retake it soon or later, if not treated properly.

Answer 2

Plants, at least some of them, provide cover and help to camouflage military forces who may hide behind or under them - think large crops, trees, canopy.

Being able to use cover to move undetected provides an advantage to the forces controlling the covered areas, and thus the opposing forces may seek ways to nullify said advantage.

There's a prime example for this: the use of Agent Orange and other herbicides in the Vietnam war.

Besides their user as cover, plants also provide food and other resources, but as the question specifies living plants only, we'll discard that, as these uses mostly require harvesting the plants. Nevertheless, denying use of these resources was also a military goal in that war.

P.S. if you happen to find a stash of potatoes, they'd be fair game for use in potato cannons - they are likely still alive.