The Enigma of Eveningsnow (Linanthus dichotomus)'s Journal

Around 1944 Alice Eastwood received word of a variant of L. dichotomus in Northern California. This original published description consisted of a population within Lake Co. with large white flowers that were open when the sun was at its meridian.

The description itself is short, with little to distinguish the different populations but a time and place mentioned by a colleague. It’s been generally understood that the most north populations acted differently that southern populations, but there was never a definite answer to how this behavior acted across the range. Somewhere along the way this variant was elevated to subspecies, and history is such; meridianus loves the sun and the day, while dichotomus thrives in the night. Meridianus is endemic and abundance in the northern coastal ranges, but not too far north and not too far coast; dichotomus loves the arid environments of the southern stretch of the state.

Meridianus itself is now known for larger petals, a different scent composition, and a smaller aperture (Chess 2008); although all these indicators are a part of a larger correlation that does not declare any single trait or character limitation that can define the subspecies beyond “yes, I AM different”. When considering habitat, I have mostly seen this plant lineage establish itself in and around the toxic outcrops of serpentine soils, it does not seem to be a good competitor against the invasive grasslands of mesic weather.

Who knew there would be such complexity. There are conflicts in specimen identifications by renowned botanists. There are tales of southern bells opening up in shaded canyons, and finicky corollas staying furled from the weather. Is it possible this definition could be so plastic? Is it possible dispersal happens across hundreds of miles on heavy pollen and wispy seeds? Maybe so. While there is no definite answer to what the exact and most efficient pollinator of this system, there is light observation and speculation: hawk moths. They travel far and wide, day and/or night depending on the species and system; opportunists, always looking for the next scent-sweetened meal. The idea of genetic exchange across large swaths of land no longer seems impossible.

Especially considering the seeds. Light, wispy, like a bubble-wrap balloon waiting to catch the next sundown wind chasing through the canyons. A trait that floats on water, to eventual sink with the absorption of enough moisture for a new generation to emerge.

I digress. This plant is fascinating, and spread far beyond the Coastal ranges above San Francisco. If you love the North, and love to reject general naturalist dogma, your challenge here is to find plants beyond Lake and Napa Co; There are known county occurrences from Shasta to Tehama, Butte to El Dorado, and I am fascinated by what these plants do and where they are. Are they the same? Are they different? Are they something entirely unique? Is it futile to try and tell them apart?

Eastwood, A., & Howell, J. T. (1944). Leaflets of western botany., v.4 1944-1. Retrieved from http://www.biodiversitylibrary.org/item/46255

Chess, S. K. R., Raguso, R. A., & Lebuhn, G. (2008). Geographic divergence in floral morphology and scent in Linanthus dichotomus (Polemoniaceae). American Journal of Botany, 95(12), 1652–9. http://doi.org/10.3732/ajb.0800118

If you’re in the southern or desert part of the range, Eveningsnow will most likely be closed during the day when you stumble upon it, although overcast days and mountain shadows can upset the understood norm. The reddish-purplish margins of the furled petals cause the plant to almost completely blend in to the background unless you really take a few moments to focus your mind and your eye. Stems are a solid reddish-purple color, with thin green (usually) tri-lobed leaves. In the evening you’ll probably smell it before you see it, as the timing of corolla unfurling and scent emission seem to happen almost simultaneously, and yes you will definitely smell it. The flowers are a beautiful pearly white, the size of a quarter or more depending on the location and rainfall. Calm night? Chill out and see who shows up! While many species have been observed showing up to these plants, hawkmoths are most likely the most effective pollinators (this statement is pending actual scientific rigor and is a gut feeling based off extensive literature research). Take a lesson from a pollinator and make time in life to stop and smell the flowers. You will most likely find this plant in sandy soil in washes or other well hydrated areas. They don’t seem to be the best at competition, so while you might find them in areas with high density grasses, it is unlikely. Currently the range is understood to be everything south of the San Francisco Bay Area, however, trends are suggesting this will be reduced to the Owens Valley, Northeast into Nevada and Northern Arizona, and Western parts of the Mojave into the southern rim of the Central Valley and Carizzo Plain.

Do you know of a naturalist community board that can use some flair? A biodiversity meeting that is looking for things to do? How about a class field trip coming up to a conservation space, or are you a lone wilderness explorer?

This project requires covering a lot of space in a short amount of time, and the only way to guarantee the collection of enough data is by recruiting the public. YOU are important for this study, and your participation is essential. Feel free to print the linked flyer and post to any community space/information board that would be interested in contributing to the understanding of biodiversity in California.

Happy hunting!

Link to flyer:
https://www.dropbox.com/s/cy2jf2ejtbzmog1/HAVE%20YOU%20SEEN%20ME.pdf?dl=0

One of the most challenging parts of studying this plant is complexity found not only within this species, but at higher levels of taxonomy as well. The genus Linanthus is distributed all across the California Florirstic Province, and while there are some consistent traits that shout out “Here I am!”, the amount of differences between species is astounding. This intuitively makes sense when you start thinking about the complexity of California landscape and differences in rain patterns and temperature, the giant chains of mountains limiting the dispersal to new places, and timescales on the thousands to millions of years.

Basically, this plant looks different depending on where you are. And to add more complications, there are a few other species that look like Eveningsnow (1), but they aren’t: Linanthus maricopensis is a large lobed annual flower found in central and southern Arizona and is identifiable by the glandular trichomes on the calyx and pedicel (there are sticky hairs on the green-maroon base and stem of the flower). Linanthus bigelovii (a sneaky imposter of Linanthus dichotomus) is an annual flower that is mostly found to the East of California, although many observations have been made in the Mojave and Great Basin deserts and even up into the Coastal Ranges of California (think an hour or two south of San Jose). There are two subspecies of in this lineage: ssp johnsonii and ssp bigelovii. Linanthus bigelovii ssp. bigelovii is a small lobed flower that looks an awful lot like L. dichotomus ssp. pattersonii and usually takes additional measures to confirm identification. L. bigelovii ssp. johnsonii look a lot like linanthus dichotomus with large lobes on the corolla but has small glandular trichomes along the calyx and pedicel whereas L. dichotomus is glabrous (or hair and gland free). Last but not least is the benign offender, Linanthus jonesii. This plant has small lobed flowers and glandular trichomes all over the calyx and inside of the upper leaves, so there is no real issues with confusion unless you’re whizzing by at 60mph.

So what’s the difference, you say? How do I see snow? Specifically, there are two. The first, is the insertion of the anthers in the corolla tube. In L. dichotomus, this will be more towards the base and have a hairy nectary at the attachment point of each one (1, pg 67-68). In L. bigelovii, this will be in the middle and will lack hairs and nectaries (1, pg 63).

Too late for flower season? Check out the seeds! In L. dichotomus, the seeds are surrounded by a lattice like white covering, almost like a mini bubble wrap (1, pg 68). This membrane leaves a little space between it and the tiny little brown seed. L. bigelovii, on the other hand, has almost vacuum wrapped this white membrane to the angular seed (1, pg 62), which becomes sticky when wet. Last but not least L. jonesii has cute little brown kidney bean seeds that do not have a membrane, so again, completely different.

Ok ok, yes, you are correct: Tearing apart a corolla to find out what kind of plant it is should be left as an emergency last resort, especially since I am trying to recruit as many participants as follows. Can’t tell if it is Linanthus dichotomus? Make a note to come back and check out the seeds! If you can’t, maybe someone else can! The nice thing about plants is they don’t move, so barring a heavy wildfire or a new mini mall, the stems should still be there a few months later with at least a few seeds still waiting to be dispersed.

(1) Porter, J. M., & Patterson, R. W. (2015). A Fistful of Polemoniaceae: new names and combinations. Aliso, 32(2), 55–88.

Publication can be found online here: https://scholarship.claremont.edu/aliso/vol32/iss2/2/

Polemoniaceae is an adorable family of annual and perennial plants with almost all of its diversity found in North America. This family is known by its diversity in flower morphology and plant-pollinator relationships. Are you in to first person narratives of science theory, like Darwin? Then you will love Flower Pollination in the Phlox Family, by Grant and Grant (1). Verne and Karen were a husband-wife duo that studied and published together on all things pollination. This book is a culmination of observations, both personal and scientific, that discuss the diversity of plant pollinator systems in Polemoniaceae. While this book is somewhat outdated in its taxonomy (genomics have completely revolutionized plant taxonomy), it is beautifully written with excellent observations and personal touches, and does in fact write about Linanthus dichotomus. Great read if you like non fiction natural history books with a personal twist.

Back to the identification of Eveningsnow: Polemoniaceae is known by its 5-5-5-3 combo of flower anatomy parts: 5 sepals, 5 petals, 5 stamens (pollen producing parts), 3 carpels (chambers of ovules at the base of the flower; Can usually be counted by the lobes at the tip of the female anatomy, or where the pollen begins its journey).

See the following link for an excellent introduction to flower anatomy, brought to you by the University of British Colombia (famous for their plant research department):

http://blogs.ubc.ca/biol343/flower-structure-and-morphology/

In Linanthus, the sepals are not showy like the petals, but are instead more vegetative like in its looks with thin membranes that sometimes connect each lobe together. The leaves in this genus are needle like (not hard like a pine, but almost like mini-skinny succulents, sometimes with hairs). Flowers are all perfect (bisexual, aka both sexes present in one flower), and radial (you can draw a line almost anywhere through the middle and both sides will match). Corolla tubes are present, aka the petals are fused at the base before fanning out for show. The genus is almost entirely restricted to southern California deserts, Transverse/Peninsular ranges, and Baja, except for one species: Eveningsnow.

A great resource for aspiring botanists is the online Jepson Manual for the California Floristic Province. While it is not completely up to date it has great resources for botanical vocabulary, dichotomous keys, maps of known localities, photos and more. See the following link for the Linanthus section and don’t forget to check out the other beauties in this group!

http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=8871

(1) Grant, V., & Grant, K. A. (1965). Flower pollination in the Phlox family. New York: Columbia University Press.

The data collected by this study will be used to compare the projected geographic range of morphological characteristics with a genetic study that suggests four diverging geographic lineages within the species complex of Linanthus dichotomus. Presence-only distribution models (also known as ecological niche models) for both studies will be compared for goodness of fit and resolution of appropriate characteristics for identification.

I will be using photo recognition software, satellite imagery, and climate and soil data to better understand what is going on in this extremely complex and genuinely adorable system.

What I am looking for:
Photos of flowers straight on (if flower is open) to see aperture (opening where pollinators feed from), color, and petal morphology.
Photos of petal margins (side shot if flower is closed, underneath if flower is open) to see color.
Photos of soil (whole plant profile is fine if I can see the ground).
Photos of habitat (to see population size as well as other species coexisting).
Time of day photos are taken (looking for photos from 2019, although photos with good data from past seasons are welcome).
See a pollinator foraging? Take a photo and let me know! I will slowly be adding taxa to my study as they show up.

This project is set up to automatically aggregate all photos taken within the locality range of California, Nevada, and Arizona; all you need to do is upload each plant as a separate observation, OR leave comments on iNat/identifying markers on the photos. Best practice would be picture sets from at least 5 different individual plants; more if the population is huge, less if the population is tiny... no pressure though! No great photo will be ignored! Also, soil photos are obviously only needed once unless you see something interesting you would like to share with me.

As localities start heating up, I will be posting spotlights on floristic regions and giving more details on specific localities I am interested in getting data from. However! Do not let this deter your wanderlust. I will also be posting on excellent plant databases and ways to find new wonderful areas to explore, in case you're up for a nature challenge!

If you have any questions or comments, feel free to message me via iNaturalist (@enemjee ) or send me an email: ngraham@calacademy.org

Happy Hunting!

In order to sustain the biodiversity of life, we must first understand what it is and how it works. My research looks at the genetic and morphologic patterns that arise from differentiation within a species, which can give us clues as to how these population differences can lead to speciation. While my study organism, Linanthus dichotomus, is a common annual plant distributed across California and throughout the Southwestern United States, the occurrence of genetically different lineages provides us with a unique opportunity to explore what and how selection pressures can cause speciation. These lineages are located within a hotspot known to botanists as the California Floristic Province, distinct for its high plant biodiversity and species endemism. By studying how this species is diverging within such a unique and important region, we can shed light on the important work ahead needed to sustain the biodiversity of life.

Also known by its common name Eveningsnow, L. dichotomus (Benth) is night-blooming annual distributed across California and into Nevada and Arizona. In the northern part of the species range is ssp. meridianus (Eastwood)(1), whose flower behavior is described to open early in the day and remain open until the following morning. This behavior is in contrast to the vespertine or night-blooming sister taxon in the Mojave-Great Basin desert (ssp. dichotomus). An earlier study compared “day-blooming” (L. dichotomus ssp. meridianus) to “night-blooming” (L. dichotomus ssp. dichotomus) populations across the western contact zone of the subspecies ranges and found significant differences in floral morphology, anthesis timing, and floral scent compound ratios (2). Although these differences appear to support the recognition of the subspecies as currently delimited, several lines of evidence may distort the picture. Multiple herbarium records indicate conflicting taxonomic identification for specimens collected at the same place but during different collection events, suggesting either the anthesis trait that defines the difference between subspecies is more variable than originally assumed, or subspecies are sympatric. Genetic differentiation has been found to be higher outside the targeted range of the original ecology study, suggesting there is more morphological work to be done to fully understand this species. To add an additional angle to this system, a unique floral morphology found sympatric to desert-mountain populations of L. dichotomus ssp. dichotomus was described as L. dichotomus ssp. pattersonii (3). Corolla lobe length in ssp. pattersonii is significantly smaller than in the other two subspecies, supporting at an additional path of divergence and hinting at a larger truth to documented observations of self-pollination within the species(4).

To understand the strength and importance of environmental and ecological factors influencing speciation, one must first understand how current populations are related across a landscape and how lineages are diverging. Through this study I hope to achieve a redefinition of characteristics for unique species and subspecies identification, and gain a better understanding as to how different the habitats of these lineages truly are.

If you have any questions or comments, feel free to message me via iNaturalist (@enemjee ) or send me an email: ngraham@calacademy.org

References:

(1) Eastwood, A. & Howell, J. T. Leaflets of western botany. v.4 1944-1, (1944).
(2) Chess, S. K. R., Raguso, R. A. & Lebuhn, G. Geographic divergence in floral morphology and scent in Linanthus dichotomus (Polemoniaceae). Am. J. Bot. 95, 1652–1659 (2008).
(3) Porter, J. M. & Patterson, R. W. A fistful of polemoniaceae: new names and combinations. Aliso 32, 55–88 (2015).
(4) Grant, V. & Grant, K. A. Flower pollination in the Phlox family. (Columbia University Press, 1965).