Normally, I have references to back up comments, but I am not in my library right now to look up the article I am referencing (source: American Scientist, possibly 2015 or 2016). In any event, the article featured a type of (aerial) spectrographic analysis of rain forest tree cover that produced different spectral signatures (color variations) for different species of tree. However, this technique worked for identifying tree species via the top of the forest canopy – a canopy that is often too dense for such (aerial) spectrometers to penetrate to the ground level where rare plants may be found.
Now, the technology known as LiDAR (light detection and ranging) that uses super fast laser pulses that can indeed penetrate to the ground level (it is used to identify archeological ruins beneath dense forest/jungle cover) but does so by digitally ‘eliminating’ the vegetation cover (simplistically, by using a tuned laser system that ‘extracts’ anything green from the image). Since most plants are green, this poses a problem: how to detect ground plants from the air and also by-pass the forest canopy that obscures them?
Perhaps a ‘one-two’ punch’ type tuned laser system (Lidar + Spectrometry/spectrography) might be usable, where the first (lidar) laser pulses by-pass the canopy and a second (broadly ‘tuned’) laser pulse (stream) acts as a spectrometer or spectral ‘probe’ (e.g., Raman spectroscopy, or, Coherent Anti-Stokes Raman spectrometry, known as CARS) of the ground level vegetation (to identify new plant species or potential sites of possible new species). Lidar systems are now being mounted on drones for close-in, more precise, mapping purposes.
All that said, any type of spectrometric /spectrographic tech may likely only be usable on the ground (“close up” as it were) due to the much smaller size of plants verses tree top/canopies. Further, precision tuning would be paramount as no doubt many species of plants will have similar (or overlapping) spectral signatures. This is why, in a separate forum post, I recommended use of portable DNA sequencers (e.g., MinION, or, Nanopore technology), which could be augmented by wi-fi capability (provided by aerial wi-fi-transmitting balloons or drones connected to the an Internet/cloud database of plant DNA sequences). Cellular networks could also be employed (in conjunction with a camera-spectrography app) – assuming that cellular microwave transmissions can reach into remote forested areas.
Lastly, I also recommended (as several others have) forging contacts with indigenous peoples/tribes (known as “stakeholders”) to both identify their traditional medicinal plants, and, locate areas rich in plant diversity. Cultivating this type of cooperative relationship (in which their native land is protected and their way of life is preserved as much as possible, from outside interference) is paramount. This is a “low tech” approach that should never be over-looked in our rush to find and apply new technological solutions.
