plant material vs stalk

plant material and stalk both are nouns.

Word	Noun	Adjective	Verb	Adverb
plant material	Yes	No	No	No
stalk	Yes	No	Yes	No

As nouns, stalk is a hyponym of plant material; that is, stalk is a word with a more specific, narrower meaning than plant material:

plant material: material derived from plants
stalk: material consisting of seed coverings and small pieces of stem or leaves that have been separated from the seeds

Other hyponyms of plant material include cutin, chaff, husk, shuck, straw, stubble, cork, plant product, vegetable tallow, wood.

plant material (noun)	stalk (noun)
material derived from plants	a stiff or threatening gait
	the act of following prey stealthily
	a hunt for game carried on by following it stealthily or waiting in ambush
	a slender or elongated structure that supports a plant or fungus or a plant part or plant organ
	material consisting of seed coverings and small pieces of stem or leaves that have been separated from the seeds

plant material (verb)	stalk (verb)
	walk stiffly
	follow stealthily or recur constantly and spontaneously to
	go through (an area) in search of prey