Hello Vinay, According to my experience, I have extracted DNA/RNA from different plant tissues and is very important to consider the plant species. Different vegetal tissues contain different cellular components (which can act as inhibitors of the PCR reaction). First all, check bibliography, you can consult papers where the authors made nucleic acid extraction from a vegetal tissue from the same species that are you working.

In any case, you can use CTAB extraction. This protocol is the "Gladiator" of all the DNA extraction protocols in plants. EPPO protocol for the detection of Xylella fastidiosa (Bacterium that have most that 500 differents plant hosts) recommends this protocol.

Links:

https://onlinelibrary.wiley.com/doi/epdf/10.1111/epp.12469

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC324241/

PD: If you continue to have problems with inhibitors, try diluting the DNA extracts. That way, the inhibitors are diluted and you can get a favorable PCR result.

MagMax plant DNA isolation kit

And remember, Science is not marketing. ;)

Yeah :) Félix Morán

Extract DNA from some tree species could be a little difficult. Try some commercial kit, such as qiagen's DNeasy. At the first step, you can incubate it at 65C for more than one hour to lysis the tissue. Good luck