i learned to identify a tree in my garden with the indentification key from NHM. but it hasn't fruit and flower now ecept leafs. leafs is not enough to identify it. how should i do to indentify it in this cases? thanks.
In general, with any living organism, you may not have enough information to identify it completely. In these cases, you have to accept an incomplete identification. That may mean you know it is one of a few particular species, or you may know just the genus, or maybe even just the family.
In this case, I have just your photos as information.
I can tell from these that it is a species of Fraxinus, and I would guess Fraxinus excelsior, the common ash.
I say that based on:
- the shape of the leaves
- the arrangement of leaves on the stems
- the nature of the bark
- the nature of the bud scales (the buds now having expanded and given rise to new branches)
- its jizz
In all those things, I am using experience.
Everybody's experience is different. I may have more than you, but other folks will have more than me.
To answer your 'How should i do to indentify it in this cases?'
1. Accept that it might not be possible
2. Accept that it might be possible to make only a partial ID, eg. as far as genus
3. Consider some of the things I menion above
4. Consider other things, eg.:
- look for old fruit/seeds/flowers below the tree (they may be decomposing but they can still be useful)
- consider the acidity of the soil (some plants grow only on acid or on basic soils)
- consider the location (some plants have limited distributions)
- consider the environment (some plants live in particular settings, eg. woodland)
5. Refer to books and online information resources