Wild Blue Phlox, Louisiana Blue, Woodland Phlox, Wild Sweet William 

Phlox divaricata

(Phlox divaricata subsp. laphamii)

floks  dy-vair-ih-KAY-tuh

Synonyms of Phlox divaricata (2) (Updated on 12-22-23 from Plants of the World Online): Armeria divaricata (L.) Kuntze, Phlox vernalis Salisb.
Synonyms of Phlox divaricata subsp. divaricata (10) (Updated on 12-22-23): Phlox canadensis Sweet, Phlox divaricata f. albiflora Farw., Phlox divaricata f. albiflora House, Phlox divaricata f. albiflora D.M.Moore, Phlox divaricata f. bicolor J.W.Moore, Phlox divaricata var. canadensis (Sweet) Wherry, Phlox divaricata f. candida E.J.Palmer & Steyerm., Phlox divaricata f. coulteri Fernald, Phlox divaricata f. purpurea Farw., Phlox glomerata Nutt.
Synonyms of Phlox divaricata subsp. laphamii (2) (Updated on 12-22-23): Phlox divaricata var. laphamii Alph.Wood, Phlox laphamii (Alph.Wood) Clute

Phlox divaricata L. is the accepted scientific name for the Wild Blue Phlox. The genus and species were both named and described as such by Carl Linnaeus in the first volume of the first edition of Species Plantarum in 1753.

Accepted infraspecific names of Phlox divaricata (2) (Updated on 12-22-23): *Phlox divaricata subsp. divaricata (autonym), Phlox divaricata subsp. laphamii (Alph.Wood) Wherry. *When an infraspecific taxon is named, an autonym (“type-specimen”) is automatically generated whose description is closest to the (original) species. All have their own synonyms.

Phlox divaricata subsp. laphamii (Alph.Wood) Wherry, was named and described as such by Edgar Theodore Wherry in Baileya in 1956. It was first named Phlox divaricata var. laphamii by Alphonso Wood in the second edition of A Class-book of Botany in 1847. 

As of 12-22-23 when this page was last updated, Plants of the World Online lists 68 species in the Phlox genus. It is a member of the plant family Polemoniaceae with 27 genera. Those numbers could change periodically as updates are made by POWO. 

The above distribution map for Phlox divaricata subsp. laphamii is from the USDA Plants Database. The map is not the same as for Phlox divaricata subsp. divaricata (autonym) and unlikely grow in Missouri. The map on Plants of the World Online doesn’t show Kentucky when I last updated this page

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as members post new observations.

THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH A BETTER POSITIVE ID.

Phlox divaricata is a perennial species that typically grow up to around 30″ or so tall. They have a stoloniferous root system that multiple stems grow from to form small clonal colonies. They prefer growing in light shade in fairly organic and damp soils like along creeks and streams in low areas of the woods.

There are several areas where Phlox divaricata is growing in nice colonies along the highway west of town. Where I live, there is a colony of Hesperis matronalis (Dame’s Rocket) which is easily mistaken for Phlox from a distance. The main difference right off is Phlox has five petals and the Hesperis has four. Phlox is in the Polemoniaceae Family while Hesperis matronalis is in the Brassicaceae Family.

A friend of mine lives along a highway with several nice colonies and I wanted to stop and take photos many times but didn’t. He has a nice secluded section of woods that I observed many wildflower species in including Phlox divaricata. That is where I took these photos.

The plants I observed in the woods are the subspecies Phlox divaricata subsp. lampamii because it has “rounded” corolla (petal) lobes. Phlox divaricata subsp. divaricata has notched corolla lobes… If you scroll down to the bottom, there are links to both under Illinois Wildflowers.

Flowering stems are topped with a rounded cluster of 8-25 flowers. Each flower is about 1” in diameter and has a corolla (petal) with 5 lobes, a hairy calyx with five teeth, 5 stamens, and a pistol. You can’t see the stamens and pistol because they are inside the hole in the middle of the flower.

I noticed the petals of the flowers of several plants I observed had wavy tips or even a slight point…

A calyx, also known as calyces, surrounds the flower tube which is “narrowly tubular”. The plants flower from April through June and are scented.

The above photo, although somewhat blurry, shows the underside of the corolla with its floral tube…

The above photo shows long petioles emerging from leaf axils leading to the inflorescence (flower cluster). You can see a pair of smaller leaves where the flowers emerge.

Reading the descriptions of the leaves on Missouri Plants was somewhat exhausting. In layman’s terms, the leaves on both fertile and infertile stems grow in an opposite manner along the stems and, of course, are somewhat variable… I am beginning to dislike the word “variable”.

Phlox divaricata grow two types of stems, fertile (flowering) and infertile. The infertile, or vegetative stems, are somewhat decumbent (lying on the ground then pointing upward) and root at the lower nodes. These stems have short, appressed to curved hairs (pubescent). The flowering stems stand erect, have 4-6 nodes, and have turned or crinkled hairs that may have glands on the tips. 

The base of the leaves are sessile (no petioles) and they may even clasp the stems slightly. The hairs on the leaves may disappear with age.

Phlox species are cross-pollinated by bees, butterflies, and moths that feed on the nectar from the flowers. Several species of beetles and caterpillars feed on their leaves.

I have enjoyed photographing and learning about the many wildflowers growing on the family farm and in other areas. The farm is in Windsor, Missouri in Pettis County (Henry County is across the street, and Benton and Johnson aren’t far away). I have grown over 500 different plants and identified over 250 species of wildflowers (most have pages listed on the right side of the blog). I am not an expert, botanist, or horticulturalist. I just like growing, photographing, and writing about my experience. I rely on several websites for ID and a horticulturalist I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. Some sites may not be up-to-date but they are always a work in progress. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you especially if you notice something is a bit whacky

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE
(GENUS/SPECIES/SUBSP.)
INTERNATIONAL PLANT NAMES INDEX
(GENUS/SPECIES/SUBSP.)
TROPICOS (GENUS/SPECIES/SUBSP.)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
USDA PLANTS DATABASE
MISSOURI BOTANICAL GARDEN
MISSOURI PLANTS
iNATURALIST
WILDFLOWER SEARCH
DAVE’S GARDEN
FRIENDS OF THE WILDFLOWER GARDEN
ILLINOIS WILDFLOWERS
(subsp. divaricata/subsp. laphamii)
MINNESOTA WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
IOWA PLANTS
PFAF (PLANTS FOR A FUTURE)
GO BOTANY
LADY BIRD JOHNSON WILDFLOWER CENTER
FLORA FINDER
UNIVERSITY OF WISCONSIN
GARDENIA
OZARK EDGE WILDFLOWERS

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is one of the most reliable and up-to-date plant databases and they make updates regularly. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂