the vertical tendency, Goethe used the term 'spiral tendency'.

To help towards a clear understanding of both tendencies, Goethe
describes an exercise which is characteristic of his way of schooling
himself in what he called exact sensorial fantasy. He first looks out
for a phenomenon in which the 'secret' of the spiral tendency is made
'open'. This he finds in such a plant as the convolvulus; in this kind
of plant the vertical tendency is lacking, and the spiral principle
comes obviously into outer view. Accordingly, the convolvulus requires
an external support, around which it can wind itself. Goethe now
suggests that after looking at a convolvulus as it grows upwards around
its support, one should first make this clearly present to one's inner
eye, and then again picture the plant's growth without the vertical
support, allowing instead the upward-growing plant inwardly to produce
a vertical support for itself. By way of inward re-creation (which the
reader should not fail to carry out himself) Goethe attained a clear
experience of how, in all those plants which in growing upwards produce
their leaves spiral-wise around the stem, the vertical and spiral
tendencies work together.

In following the two growth-principles, Goethe saw that the vertical
comes to a halt in the blossom; the straight line here shrinks
together, so to say, into a point, surviving only in the ovary and
pistil as continuations of the plant's stalk. The spiral tendency, on
the other hand, is to be found in the circle of the stamens arranged
around these; the process which in the leaves strove outwards in spiral
succession around a straight line is now telescoped on to a single
plane. In other words, the vertical-spiral growth of the plant here
separates into its two components. And when a pollen grain lands on a
pistil and joins with the ovule prepared in the ovary, the two