This type of travel is really a throw back to the old plant collector/explorer tradition...when travelers would collect plants for scientific or botanical use in their home countries.
The English sent many plant collectors to the Americas...and to China, Tibet and Nepal...in the 18th and 19th Centuries...
Of course plant material needs to be declared at customs... So it many not make it into your home country...if it is considered risky to domestic agriculture...
I managed to get customs to approve a pint of dry Serbian beans from a market in Belgrade recently...which I planted successfully the following year... I've also got a sprig of ivy from near Kafka's grave in the Prague at the New Jewish Cemetary...which is thriving nicely.
I've seen several plants on trips that I have only seen in garden centers...an example is the "sensitive plant" whose leaves close up when touched... This low and spreading plant grows all over the river banks in Cambodia...sort of like a lawn weed really...I noticed it by accident while climbing up a river bank in Siem Reap after the night of the Water Festival...
So collecting or not...being aware of local plants can be interesting...and plants can't run away like local animals or birds...
