Help me distinguish Romneya–Fried Egg Flowers
Genus Romneya (ROM-nee-uh) in family Papaveraceae (Pah-pah-ver-AY-see-ay, the poppy family) contains only two species. Known as Matilija (in Spanish, mah-teel-EE-ha, although I hear English-speakers say mah-TIL-i-ha) poppies or Fried Egg Flowers, these large, sweet-smelling flowers consist of six crinkled, white, crape-paper-like petals surrounding a pom-pom center of deep golden stamens. A single petal can be 10 cm (4 in) long. They are the largest flowers in the poppy family, and the largest flower native to California. The state legislature of California nominated Romneya as one of the possibilities for state flower, but ultimately awarded the title to Eschscholzia cailifornica.
A Romneya coulteri bloom
A Romneya trichocalyx bloom
Romneya are large shrubs, up to 2.5 m (8 ft) tall, restricted in native range to southern California and northern Baja California. Small range, combined with the unique, memorable flowers, easily recognized by casual observer and AI alike, mean nearly all observations on iNaturalist labeled “Romneya” are correct to genus. Observations of the plant north of Santa Barbara county are cultivated (see maps in Jepson links below). The plant is cultivated all the way up to the top of Washington State, but difficult to obtain and grow outside the west coast, so observations elsewhere are definitively misidentified. Incorrectly labeled plants are most often white garden peonies, and sometimes white-flowered species of Argemone (a different poppy genus, with very prickly leaves, resembling those of thistles.)
The tricky part is splitting Romneya observations into the two species: Romneya coulteri, and Romneya trichocalyx. For definitive ID, the observation must include an in-focus and fairly close-up shot of an unopened flower bud, to see whether or not the outside of the bud is hairy. The buds of R. coulteri are always completely smooth/not hairy. The buds of R. trichocalyx are always hairy. In fact, the Latin name trichocalyx means “hairy bud,” from trichomes (botanical term for hairs) + calyx (the collection of green, leaf-like appendages enclosing a flower bud, also known as sepals.) When I change the ID on an iNat Romneya observation, I briefly explain this smooth bud/hairy bud distinction.
UPDATE: today I realized it may be possible for some people to confuse the seed pods for unopened flower buds, since the shape is a bit similar. Please look carefully, because the seed pods are hairy in both species!
No hairs on Romneya coulteri. This is also the wide-leaf form, as discussed below.
Hairs on Romneya trichocalyx. Don’t be distracted by the narrow leaves of this plant; see discussion below.
Wait, is that it? Just one characteristic, either hairy or not hairy flower buds?! Yes, that’s it. Or at least, the presence or absence of hairs on the flower buds is the only hardline rule and the easiest to capture in photos. There are other differences that vary a little more, and don’t make as good pictures, including:
- Flower bud shape: R. coulteri buds are often “beaked,” or strongly pointed on top, while R. trichocalyx flowers are often rounded/weakly pointed. This can be helpful for photos which are not in perfect focus, but I am not yet certain it is accurate in 100% of cases.
- Petal and leaf size: R. coulteri petals and leaves are on average a little larger than those of R. trichocalyx, but given the amount of variation and overlap, I don’t find this helpful even when I have the plant in person, never mind in photos!
- Seed: R. coulteri seeds are dark brown and papillate (bumpy.) R. trichocalyx seeds are light brown and smooth. This is useful in person, but I haven’t seen anyone photograph the seeds for an iNat observation.
- Dubious distinction of leaf shape: Some people will tell you R. coulteri leaves have wide lobes, whereas R. trichocalyx leaves have skinny lobes, giving their leaves an overall look that is much more feathery and finely divided. I don’t find this true. While I have seen feathery, finely divided leaves on R. trichocalyx in cultivation (my photos were taken on cultivated plants,) I almost never see them on wild plants. I think leaf shape naturally varies, and perhaps someone even selected the finer leaves for R. trichocalyx plants available for cultivation. I could understand if a nursery worker wanted an easy way to tell unblooming plants apart.
Wide lobe leaf form
Narrow lobe leaf form
So what if the iNat observation is a nice headshot of a big white flower, and nothing else? If there aren’t any buds, or if the distance or focus of the buds is not adequate to see their hairs, genus Romneya is as good as the ID can get. The flowers bloom April-June, so the next few weeks are a great time for observation clean-up. If you would like to help with clean-up, vote below:
- Yes, I want to help clean-up this genus.
- No, I am not interested.
If you would like to subscribe to maintain the taxa over time, vote below:
- Yes, I want to maintain the genus over time.
- No, I am not interested.
I would love to hear your questions or feedback. I do not consider myself a Romneya expert; for example I have no idea whether it is possible for the two species to hybridize, or whether some taxonomists might consider the two species to be one species, given their extreme similarity. What do you think? I do propagate/grow native plants for a living, so if anyone has cultivation questions about Romneya or other species, ask away (perhaps not on this thread, in effort to stick to topic.)
Genus Romneya http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=10836
Key to Romneya http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?key=10836
R. coulteri http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=41557
R. trichocalyx http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=41558
Genus Romneya http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=128724
R. coulteri http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=220011716
R. trichocalyx http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501215