The phrase "a single leaf or" is correct and usable in written English.
It can be used when discussing options or choices, particularly in contexts where you are presenting alternatives that include one specific item.
Example: "You can choose to take a single leaf or a whole branch, depending on your needs."
Alternatives: "one leaf or" or "a solitary leaf or".
On a vigorous plant, pinch them back to a single leaf or pair of leaves.
But we've all had that feeling of bewilderment — looking at a single leaf or a piece of wood and thinking that the entire history of the universe was captured within it, and how could that be?
This is a harrowing and stupendous journey: from Timbuktu to Araouane, a town founded in 1575 at a group of wells where caravaners have been stopping for thousands of years, and on to the salt mines of Taoudenni, "situated on utterly lifeless desert flats; not a single leaf, or even thorn, grows from the parched, crusty dirt, which was so sharp it bit into the soles of my bare feet".
Seedlings that contained an empty apex, a single filament, a single leaf or two leaves in place of a viable shoot meristem, were scored as showing stem cell defects, as per previous studies [ 8, 10].
Phenotypes range from an empty apex to a filamentous structure, a single leaf or two leaves in place of the SAM, together with a fraction of individuals that develop a fully functional shoot meristem [ 8].
For example, although several factors might be involved in driving a response of a leaf to an experimental treatment (e.g. herbivore presence, light availability, etc)., the effect size of a leaf-level response such as leaf N content is modified primarily by chemical processes occurring inside of a single leaf or stem (e.g. Reid et al. 1998).
Net photosynthetic rate (A) values on a single-leaf or whole-canopy basis in field-grown papaya were similar and highly correlated under clear sky conditions since the open canopy architecture of papaya plants allowed saturating light intensities for photosynthesis to reach all leaves.
For strap-leafed ferns in the genus Elaphoglossum, each ramet was a single leaf, while ramets for other taxa consisted of one or more stems with multiple leaves.
Most species have a single leaf per pseudobulb.
It was five feet tall and bore not a single leaf.
"In forests, there's not a single leaf on the trees," she said.
