I my experience, there are some lab works which not require much equipment. For example the detection of saponins.
Cheok Ch, Salman H, Sulaiman R. 2014. Extraction and quantification of saponins: A review. Food Res Int. 59:16-40.
The use of vegetal extracts to obtain inmune response in rabbit is another interesting experiments and was used in the past with taxonomic purposes.
Gell, P. G. H., Hawkes, J. G., & Wright, S. T. C. 1960. The application of immunological methods to the taxonomy of species within the genus Solanum. Proceedings of the Royal Society of London B: Biological Sciences, 151(944): 364-383.
The use of vegetal extracts to measure antibiotic properties could be made using strains of known bacteria and non differential agar culture.
There are many examples in the literature of qualitative analysis using simply reagents (alcaloids, pigments, cutaneous reaction, ...) which would be useful in the field simply with the aid of a portable lab kit.