Yellow-flowered stonecrops

I observed a yellow-flowered stonecrop at the edge of the Andrews Community Forest in Richmond, Vermont on 2024-07-12. It was at the trailhead but the patch was clearly growing wild. (Actually there were two distinct patches but I haven't posted the other observation yet.) In the field, I thought it might be something in genus Sedum but apparently plants in that genus have thick leaves, whereas this had flat (laminar) leaves.

Based on the iNaturalist taxonomy (which follows POWO), I now believe the observed plant is in genus Phedimus. However, authorities disagree on the taxonomy of yellow-flowered stonecrops. In particular, the genus Aizopsis is also recognized and in use. Within these genera, there are multiple taxa with no clear boundaries (at least I am unable distinguish taxa in this group).

After reviewing a handful of reliable sources, I've concluded that the observed plant is a member of Phedimus subgenus Aizoon but I can take it no further. My sources are recorded in the following document:

Yellow-flowered stonecrops (googledoc)

Hope this helps.

Posted on July 17, 2024 01:15 PM by

trscavo

Observations

Photos / Sounds

5 photos

What

Subgenus Aizoon

Observer

trscavo

Date

July 12, 2024 12:27 PM EDT

Place

Chittenden, Vermont, United States (Google, OSM)

Description

Andrews Community Forest, one of the Richmond town forests

Needs ID

View

Comments

I think this is P. ellacombeanus because the carpels of P. kamstschacticus, such as the variegated one here, tend to become orange-tinged. They remain yellow in P. ellacombeanus. Also, P. kamstschacticus leaves usually have more teeth than those on the specimen in your photo.

However, specimens of this genus, formerly Sedum, are difficult to identify because their phenotype varies immensely - specimens of any of the above mentionned variety can have elongated or rounded leaves and sharp or wavy teeth. Their height and spread also varies greatly according to their environnment. Just try collecting seed from a specimen, sow them and you may be impressed by the variations.

NB
Speaking from experience of having collected sedums some 40 years ago, (my extensive documentation and plant collection now lost) as well of decades of shopping and planting great many varieties, cultivars and hybrids in landscaping projets as well as my personal garden. At time they were all Sedum, but now also Pheduim and Hylotelephium.

Posted by sygrnwd about 2 months ago

Thanks @sygrnwd I appreciate the ID and the comments

Posted by trscavo about 2 months ago

Addendum to my comments
From experience, plant id labels from nurseries are not usualy reliable and often just plain wrong.
Best reliable, albeit dated, reference that I know of for stonecrop identification is Sedum: Cultivated Stonecrop by Ray Stephenson