How I identify Eschscholzia
Here is my own quick and dirty approach to recognize the common forms of these plants.
Please, anyone, feel free to make suggestions.
The most helpful photos show:
1) the side of the receptacle at a low enough angle to see the bottom of the flower
2) the whole plant from base to flower to clearly see the flower stem, the leaves at the base, and the leaves on the stem
3) a flower bud fine enough detail to see any hairs
4) some way to tell the difference between a 6mm versus 15mm versus 30mm flower petal
Common misidentifications:
Any plant with a simple stem, no leaves, and only one flower can be misidentified as E. glyptosperma or E. lobbii.
E. caespitosa: iNat on a phone will sometimes suggest E. caespitosa when it is clearly E. californica, but on the website the same photo will be identified as E. californica.
E. parishii: some specimens near Joshua Tree NP are really E. papastillii
E. ramosa: some people will call anything found on the Channel Islands the Island Poppy, but E. californica is all over the islands.
Receptacle rim > 0.5mm (except maybe near Joshua Tree NP),
petals well over 25mm
fancy colors (red or white)
growing anywhere outside CA, OR, NV, UT, AZ, NM, northern Mexico
--> E. californica
Bell-shaped receptacle with a rim, thin cauline leaves, near Joshua Tree NP
--> E. papastillii
Single flowers on simple stalks with no cauline leaves,
basal leaves broom-like,
desert areas
--> E. glyptosperma
Receptacle with significant parallel sides
--> E. lemmonii (because I don't ever expect to see E. rhombipetala).
Hairy, nodding bud
--> E. lemmonii ssp lemmonii
Hairy, nodding bud or petiole (when not E. lemmonii)
--> E. hypecoides
On Channel Islands (and a couple off the coast of Baja),
short and thin leaf segments,
short bud
--> E. ramosa
Full growth like E. california but with no receptacle rim and petals to 25mm,
in CA west of the deserts and OR south of Eugene,
but not San Francisco, San Mateo, Alameda, or Contra Costa counties (don't know why)
--> E. caespitosa
Single flowers on simple stalks with no cauline leaves, basal leaves only,
petals to 12mm, sometimes pointed petals,
Sierra foothills
--> E. lobbii
Note: I'm not always certain E. lobbii versus E. caespitosa since the ranges overlap.
Narrow basal leaves,
really, really narrow cauline leaves with few lobes,
desert areas
--> with bell shaped receptacle with rim and near Joshua Tree NP --> E. papastillii
--> regular tapered receptacle no rim --> E. parishii
Wider basal leaves,
cauline leaves small but with wider lobes,
desert areas
--> tiny flowers --> E. minutiflora
--> larger flowers and near Joshua Tree NP --> E. androuxii
Dark spot at center of flower can be either E. androuxii or E. glyptosperma
I have not figured these out yet
E. californica ssp mexicana: seems like some people use this for many poppies in Arizona.
If you show me photos of a Mexican Poppy and a Tufted Poppy without location information I don't know if I can tell them apart.
E. rhombipetala: no observations in iNat but does exist in 2 places in California.
Reference for most identifications (Jepson eFlora)
https://ucjeps.berkeley.edu/eflora/eflora_keys.php?key=10827
Reference for E. androuxii and E. papastillii (Still 2014)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4023337/
