Aside from the human figure, trees are some of the natural forms artists find most interesting, and they have been drawn and painted in a myriad ways.
St Louis artist Mary Sprague creates ink drawings, sometimes in colors, often monochromatic, in which delicate sprays of line and hatching coalesce to create her tree forms.
When seen at the scale at which her work is reproduced on her website, her groupings of short but flowing lines, and the way she applies them in textural passages, give her drawings some of the feeling of softness and delicacy characteristic of etchings.
I suspect, given the scale of her previous work, that these drawings are relatively large, and some of the feeling of the line comes from the relationship of the size of her drawing tools ot the size of the composition.
In her online galleries you will also find older work with different subject matter. In particular a previous series centered on large scale ink drawings of chickens. These are occasionally worked in color with brush and either watercolor or colored inks.