In article ,
Iris Cohen wrote:

What about pawpaw (_Carica papaya_) "trees" which are really very large
herbs?

Pawpaw is Asimina triloba, a member of the Annonaceae, definitely a tree.
Carica papaya, the papaya, is referred to as a plant, not a tree, same as a
banana plant.

In the US, Carica papaya is called papaya, and Asimina triloba is
called pawpaw, or papaw, which is a corruption of the Spanish word
papaya, meaning the fruit of C.papaya, derived from its name in a
Cariban language. In Australia and some other parts of the English
speaking world, C.papaya is called pawpaw, and A.triloba is unknown.

In a more general sense, the same applies to the English word "tree",
which is not really a botanical term. Comparable words in other
languages, especially non-Indo-European languages, won't refer to quite
the same set of plants.

The real world is a messy place with fuzzy edges. Plants just grow and
evolve, and are not concerned with what they are called in English. We
try to shove them in labelled boxes but there's always a few toes of
socks and other odds and ends sticking out because we're imposing an
artificial distinction on reality.

So-called trees have evolved in many unrelated taxa. It's a term of
convenience for us. The genus Ficus, for example, has trees, shrubs,
vines and creepers in it. Lots of temperate climate plants grow as
shrubs or trees. A coppiced tree may grow back as technically a bush,
multitrunked, even if it gets 20 meters tall. The wood of a pine, though
a gymnosperm, looks a lot more like the wood of an oak (angiosperm) than
oak wood looks like the spongy fibrous stuff that makes up the trunk of
the angiosperm palm tree. Bamboo is better wood than palm trunks, and can
grow as tall, but it's a mere grass, even if it is much more useful as
timber.

Arguing whether Weltwitschia is a tree is fun, but it's playing with
words, not botanical reality.