In Jainism, a normal tree usually has one soul (one jīva). But some plant-bodies can have many souls — these are called sādhāraṇa vanaspati.

Simple distinction

• Pratyeka vanaspati: one plant body = one soul
• Sādhāraṇa vanaspati: one plant body = many souls sharing one body

Examples of plants commonly explained as sādhāraṇa vanaspati

• onion
• garlic
• potato
• ginger
• turmeric
• sweet potato
• other tubers, bulbs, and similar root forms

So, can a tree have more than one soul?

• Generally, a tree is considered to have one soul.
• But some plant forms do have multiple souls in one body, according to Jain doctrine.

If you want, I can also explain the difference between pratyeka vanaspati and sādhāraṇa vanaspati in very simple terms.