Aven Identification

I asked Stewart Wechsler for some tips on differentiating between Avens. I'm shaving what he shared because it's very helpful and I know I'll need to refer to it again in the future!

First the basal leaves of G. macrophyllum usually end in one big leaflet, and those of G. urbanum usually end in 3 leaflets. While the final leafets may not be the most reliable, and consistent, feature, it doesn't require a flower stalk to have developed, and can be spotted from further away than the hairs. Then the petiole and rachis (extension of the petiole between the leaflets of a pinnately compound leaf), and the flower stalk of G. macrophyllum have long, spreading, white hairs. G. urbanum has small, inconsequential hairs, that aren't that easy to notice. On the flower stalk of G. macrophyllm there are leafy stipules connecting the bases of petioles to the flower stalk, that are tear-drop shaped, might be 1 cm long, and twist up 45 degrees. Those of G. urbanum are round in outline, about 2 cm long, toothed, and horizontal. They look like one more pair of leaflets at the base of the petiole. Also the upper sides of the bases of the petioles of G. urbanum are usually red pigmented, while those of .G macrophyullum are green.

The red on upper side of the base of the petiole of G. urbanum is on leaves at the base of the plant, (or on rosettes before a flower stalk develops).

Here is a good example of the large, more or less rounded, horizontal stipules of G. urbanum:

https://www.inaturalist.org/observations/85616879

It also seems that a feaure of the seeds is being highlighted that I haven't figured out yet. The 3rd photo here shows the smaller, tear-drop shaped stipules of G. macrophyllum:

https://www.inaturalist.org/observations/114821055

It looks like the seeds or "achenes" of G. macrophyllum have straighter tips: https://www.inaturalist.org/observations/56595530

And those of G. urbanum (4th photo) have more curled tips:
https://www.inaturalist.org/observations/85616879

Adding some of Stewart's comments on additional observations:

https://www.inaturalist.org/observations/98732909

Rather than one large final leaflet, 3 palmate final leaflets, hairs on petioles, and stalk shorter than on G. macrophyllum, stipules at base of petioles larger, rounder, and more horizontal than G. macrophyllum. Unlike the smaller, upward angled, tear-drop shaped stipules of G. macrophyllum, stipules, suggest a pair of leaflets at base of petiole, also attached to the stalk, as G. urbanum stipules suggest.

AJ Wright's notes:

https://www.inaturalist.org/observations/25235298

In this case, the main distinction is that the basal leaves have terminal leaflets fully tripartite. The petals are also smaller than G. macrophyllum, the leaves often darker in color, and the habitat a bit drier. It also forms solid mats with more regularity.

Publicado el mayo 7, 2022 05:18 TARDE por leshell