I’m a plant observer/identifier… during my time on iNat the way I’ve expanded my own knowledge of plants has changed quite a lot.
When I first started out sometimes identifiers would give a tip of info here or there. Oftentimes you can ask around and most will be happy to explain their identification/share their knowledge, especially to those who want to listen.
Nowadays, I’ll often look through observations with comments in them, because often there is useful information on identification shared within observations. Usually they’ll be favorited so I sort by favorites in the filter. And then I’ll favorite those observations too. I’ve found tons of useful IDing information this way, and often they can explain it in a way that is easier for the average user to understand.
This is why it’s useful to familiarize yourself with people in your local iNat community… you’ll start to learn who is experienced in what and know what you can ask of them.
Eventually I began having to look through literature—keys, flora books, research papers, etc. At this point I started having to track down all the technical botanical jargon. It takes a lot of effort to understand what is being said in a key/scientific literature, especially for someone like me who's rarely ever done so before.
Luckily there are a lot of websites that can help with that, such as GoBotany as @vreinkymov said. Even then, you might not have enough on hand for a proper identification. To make it easier, I recommend working from both regional and more comprehensive sources (aka Flora of North America).
It is also important to not just study scientific literature but to also apply it to the field.
You can try looking at RG iNat observations, but there are always misidentifications so you can never really be sure of accuracy, especially for more difficult taxa (depends on observer and identifier of obs as well, another good reason to know your iNat community). Herbarium specimens also work but I find them more difficult to study compared to having a live, fresh, specimen in your hand.
Once I obtain useful identification knowledge, I’ll go out into the field and check it myself, look at the characteristics mentioned. Only then can you really get confident with this new knowledge.
For example, earlier this year I was trying to determine the differences between *V. persica* and *V. polita*, which both occur in my area.
I started by checking through observations in my local community-ish (within a metro area, region, state/province, etc.), under the taxon V. polita (the more uncommon one in my location), sorted for number of favorites, and looked for observations with comments. I found a few observations with useful information (here and here) based on relative length/shape of sepals, overlap of corolla lobes (aka petals), and possibly leaf margins. I also checked the person who was giving the information, who is a Professor in Germany who had studied the genus Veronica for ~20 years.
Having done this, I began checking speedwells I saw for these characteristics, and made several observations on both species (Here’s an observation I made for V. persica and for V. polita) until I was confident in my ability to correctly identify the two.
Also every now and then when I'm searching up a species on the internet I'll find useful identification information, but I check it with species descriptions from other sources just to be sure.
*Edited lightly for readability… I curse my concision problems!
