The phrase "a single branch of" is correct and usable in written English.
It can be used when referring to one specific part or division of a larger organization, system, or concept.
Example: "The research focused on a single branch of the family tree, tracing the lineage back several generations."
Alternatives: "one division of" or "a specific sector of".
That would concentrate far too much power in a single branch of government.
It was meant to hold a single branch of plum tree blossoms.
Similarly, a vase with a single branch of peach blossom or other flowers may be set out with care.
She said that the administration's position that the courts could not examine individual detainees' cases "serves only to condense power into a single branch of government".
The British government will remain unable to persuade a single branch of a single bank it owns to open for a single hour on Saturday mornings.
An exception is a small painting of a single branch of peonies, shown upside down with a pair of open cutting shears.
The different races were, in his view, branches of a single tree or, more accurately, twigs of a single branch, for the tree itself was not just the human family tree, but the tree of life.
And just as floral arrangers have turned away from voluptuous mixed arrangements in favor of a single branch or one-of-a-kind flowers or leaves, outdoor gardeners are doing the same with their pots.
For datasets in which a single branch was of relatively greater length, violating the model of sequence change degraded performance of the four approaches (Table 2).
The authors test all 19 genes of the HOG pathway with the free-ratio model of codeml (apparently for a total of ~19*7 comparisons), and identify a single gene at a single branch (MSN2 of Calb) with dN/ dS > 1.
These four isolates are clustered closely on a single branch, indicative of a recent common ancestry.
