These are plants with no tamarisk vegetation. ذَآنِينُ لاَ رِمْثَ لَهَا‏.‏

The word "dhu'nun" refers to a type of plant, and "rimth" refers to the saltwort that camels graze on. This plant grows in the tamarisk. The proverb is used to describe a people with no history or heritage, implying that no good can be expected from someone without a long history.
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This proverb is used to describe someone who has no lineage or history of good deeds or glory, from whom no favor or loyalty can be expected. A close English equivalent is:
“A tree without roots bears no fruit.”
Meaning: A tree without roots bears no fruit.
This is very close in meaning to the absence of origin and antiquity.
“Nothing good comes from nowhere.”
Meaning: Goodness does not come from someone without origin or history.
“He comes from no stock.”
Meaning: He has no lineage or respectable ancestry.
This is sometimes used disparagingly.
“Without roots, there is no growth.”
Meaning: Without roots, there is no growth or good.
“No past, no promise.”
Meaning: Someone with no past cannot have a future.
This is closer to the spirit of wisdom in the proverb.
The closest expression to the meaning of the Arabic proverb is:
“A tree without roots bears no fruit.”
“A tree without roots bears no fruit.”
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الذؤْنُون‏:‏ نَبْت، والرِّمْث‏:‏ مَرْعى ‏الإبل من الْحَمْض، وهذا الذؤنون يثبت في الرمث‏.‏
يضرب للقوم لا قديم لهم، ولا يُرْجَى خيرُ مَنْ لا قديم له‏