Introduction to the Hydrophyllaceae Family

When you learn to identify the Hydrophyllaceae family, you will quickly see some of their similarities with the Boraginaceae, which they were once included as a subfamily of until 2016.

Of all the small families split out of the Boraginaceae, this one looks the most like it, with its pretty blue and purple scorpioid cymes, especially my favorite genus Phacelia. I love their flowers, but I also love the stiff, often glandular hairs, divided leaves, and the interesting scents of the foliage in certain species, which some may consider unpleasant, but then again, for some reason I have always been biased; I tend to love smelly plants.

Common Botanical Description of the Hydrophyllaceae Family

If you’re new to plant morphology, this guide is a perfect beginner’s description, with no need to know any scientific jargon. Below this section is additional information on uses and morphology photos to help you identify the family, followed by pictures of individual species found in North America. But for researchers or those wanting to learn a more in-depth version, refer to the Scientific Botanical Description below the images for highly detailed scientific descriptions and genus-level distribution data.

Leaves and Stems of the Hydrophyllaceae: They are always herbs that grow from taproots and are often stiff or sticky-hairy and may have a noticeable scent (pleasant or not). The leaves are found on stems and at the base, rarely one or the other, and are simple (undivided) or, more often, divided into pairs of leaflets in a compound leaf and may be arranged in opposite pairs or alternately along the stem. Leaf margins may be smooth, toothed, or lobed.

Flowers of the Hydrophyllaceae: Flowers contain both male (stamens) and female (ovary, style, stigma) parts in the same flower (bisexual). They are typically arranged in coiled clusters, and their parts are typically in 5s with 5 petals and a fused calyx with 5 lobes. The flowers are often blue to violet in color and often have scaly appendages inside their tubes.

Reproductive Features of the Hydrophyllaceae: There are 5 stamens, often attached inside the floral tube with widened or appendaged bases. The ovary is superior (sits above the attachment of the petals) with a single terminal style that is usually divided into 2 lobes.

Fruits of the Hydrophyllaceae: The fruits are dry capsules that typically split apart on two valves to release their seeds.

Uses of Hydrophyllaceae 

Several members of the Hydrophyllaceae are used ornamentally, especially in shade gardens, as well as for pollinator gardens and for use in erosion control. They also produce edible young shoots and roots that were historically used by Native Americans (e.g., Hydrophyllum species) and were also used medicinally for treating mouth sores and diarrhea.

Wildlife & Ecological Values of the Hydrophyllaceae Family

The Hydrophyllaceae family provides important nectar and pollen for native pollinators like bumblebees and long-tongued bees. They also are important early-season food sources and many aid in ecological succession by stabilizing soils and slopes.

Morphology of Hydrophyllaceae in North America

So far, I have only photographed the Phacelia genus, which is the most common and representative genus in the family, so all of these morphology photos are from that genus.

Some Hydrophyllaceae Species Found in North America

Phacelia bipinnatifida—Purple Phacelia

The purple phacelia is a biennial herb up to 61 cm tall with showy rotate lavender-blue flowers up to 2 cm across, with appendaged stamens that often look fuzzy. It is typically found growing in cool moist woods and is native to the southeastern United States; this one was in a forest in Georgia.

Phacelia congesta—Blue Curls

Blue curls is a leafy annual or biennial 30-90 cm tall with purple to lavender-blue deeply lobed flowers with stamens that extend beyond the lobes. Flowers occur in heavily congested scorpioid cymes, which uncurl as the flowers bloom. Leaves are deeply cut and may appear rough. It is native to New Mexico, Oklahoma, and Texas in the United States and south into northern Mexico.

Phacelia crenulata—Notch Leaf Scorpionweed

This species is an aromatic annual, up to 80 cm tall, coated with stiff, glandular hairs. Leaves are oblong with wavy edges and get smaller up the stem. Flowers are purple or blue and may have a white throat. Stamens and style extend past the flower lobes. This native species has a disjunct distribution, found in the southwestern USA and northern Mexico but also in Peru, Bolivia, and Chile in South America.

Phacelia hirsuta—Fuzzy Phacelia

Fuzzy phacelia is a small native annual known for its dense covering of stiff but non-glandular hairs. It only grows to about 45 cm tall, may or may not be branched, and the leaves are alternately arranged and deeply lobed to pinnately compound. This cute little Phacelia is an endemic native of the south-central United States; I found this one in Arkansas.

Phacelia integrifolia—Gypsum Phacelia

People often easily identify this native Phacelia by its glandular hairs, which most find malodorous (but not me!) and sticky to the touch. It has leafy stems with simple leaves with crenate margins that often fold to the back of the leaf. It has the usual purplish to bluish scorpioid cymes of the family. It is native to the southwestern and south-central USA and northern Mexico, but most populations appear to be concentrated around New Mexico.

Phacelia linearis—Linearleaf Phacelia

This Phacelia is native to the Pacific Northwest of the USA and British Columbia and Alberta, Canada. It is easily identified by its location as well as its linear leaves, which are not common in the genus and are just visible (blurry) beneath the flower in this photo.

Phacelia popei—Pope’s Phacelia

This lovely Phacelia is one of my favorites, for its intense purple (sometimes pink) flowers in the usual scorpioid cymes. It is an annual that only grows to about 40 cm tall with leaves that range from “normal” to rather wide and pinnately divided. It is a somewhat rare species, found only in New Mexico and western Texas and just south of the border into northern Mexico.

Scientific Botanical Description of the Hydrophyllaceae

Habit & Leaf Form of the Hydrophyllaceae Family

The Hydrophyllaceae are annual, biennial, or perennial herbs growing from taproots with erect to prostrate stems, usually with an indumentum that is scabrid, hispid, or glandularly hairy, and sometimes the hairs can sting (e.g., as in Phacelia) and often have noticeable scents, from pleasant to unpleasant.

Leaves are simple to bipinnately compound, basal and cauline both (rarely only one or the other), and are arranged oppositely or alternately along the stem. They can be simple, but most are usually bipinnately divided. Secondary venation is typically palmate, and there are no stipules. Lamina margins may be smooth, toothed, or lobed.

Flowers of the Hydrophyllaceae Family

Flowers are bisexual and are arranged in terminal or axillary thyrsoidal, usually helicoid or scorpioid cymes that are sometimes congested. There are generally no bracts or bracteoles.

Flowers are usually 5(4)-merous. The calyx is fused at the base or nearly to the tip, with usually 5 lobes, linear to cordate, with valvate aestivation, and is generally persistent and enlarging in fruit.

The corolla also typically has 5 lobes, is rotate to cylindric, is generally deciduous, and often has paired appendages in the tube between the filaments. The corolla is also fused into a tube with lobes, often blue or blue-violet to purple but can also be white, pink, or yellow; corolla scales are present, small, or absent, and aestivation is contorted or imbricate.

Androecium of the Hydrophyllaceae Family

There are typically 5 stamens of equal or unequal length, with filaments that are often expanded and/or lobed at the base, often with scaly appendages, and they are typically epipetalous (adnate to the corolla tube).

Gynoecium of the Hydrophyllaceae Family

The Hydrophyllaceae gynoecium usually comprises a superior ovary, 1-2 carpels, with 2 swollen placentas with axile or (stalked) parietal placentation; usually placentation is intrusive parietal. Sometimes the ovary may appear 2-5-chambered via the intrusive, swollen placenta, but it does not appear lobed or only shallowly so. A nectar disc is often present at the ovary base, but it is sometimes reduced to glands. There is 1 terminal style, usually divided about halfway with punctate, capitate, or capitate-funneliform stigmas. There are 2 to many ovules that are epi-/apo-/pleurotropous, with integuments ca. 6 (-12) cells across.

Fruit of the Hydrophyllaceae Family

The fruit is always a dry membraneous capsule; it may be septicidal or loculicidal, generally with 2 valves, 1 to many seeds. Part of the persistent calyx is adnate to the fruit. Seeds ruminate by the inpushing of the exotestal cells/endothelium; exotestal cells are thickened on inner and radial walls; endotestal cells are persistent. The endosperm is variously copious to scanty.

Taxonomy of Hydrophyllaceae

There are about 320 species in 12 (16) genera in the Hydrophyllaceae family in the Boraginales order of the core eudicots (dicots). This family has been treated as distinct from Boraginaceae and then as the Hydrophylloideae subfamily of it. However, a 2016 revision based on modern phylogenetics has confirmed its status as a distinct family, including the removal of the Namaeae as its own family, the Namaeceae. For more information, check out Luebert et al. (2016) in the references for a great explanation and justification of the split. ‌

Genera of the Hydrophyllaceae:

Draperia (1), Ellisia (1), Emmenanthe (1), Eucrypta (2), Hesperochiron (2), Howellanthus (?), Hydrophyllum (10), Nemophila (13), Phacelia (206), Pholistoma (3), Romanzoffia (5), and Tricardia (1).

Key Differences From Similar Families

The Hydrophyllaceae had been included as a subfamily of Boraginaceae before, though it has recently been made a separate family again. They have very similar-looking scorpioid inflorescences in similar blue-to-violet colors. However, their fruits differ because Hydrophyllaceae always produce a dry, dehiscent capsule, while the Boraginaceae mostly produce indehiscent nutlets, and the Boraginaceae typically have a deeply 4-lobed ovary with a gynobasic style, while the Hydrophyllaceae have a mostly unlobed ovary with a terminal style with 1-2 stigmatic branches.

The Heliotropiaceae has also recently been split out of the Boraginaceae, and it too has scorpioid cymes. However, it can be distinguished from the Hydrophyllaceae by its terminal style with a unique cone-shaped stigmatic head and basal ring-shaped stigma that may be sterile at the tip (the stigma is not terminal) and fruits that are mostly fleshy drupes with 4 stones or are dry schizocarps.

The Namaeceae was, until recently, included as a tribe when the Hydrophyllaceae was the Hydrophylloideae subfamily in the Boraginaceae, but it too has now received family status. This small family is mostly shrubs or small trees (with the exception of Nama which is herbaceous), and they have only simple, cauline leaves, not basal. They also have 2 stylodia, or their style is united for 3/4 of its length with two stigmatic branches.

The Ehretiaceae and Cordiaceae are also recent splits from the Boraginaceae, but these families are both mostly shrubs and trees instead of herbs, and both mostly produce fleshy drupes for their fruits instead of dry capsules.

Distribution of Hydrophyllaceae

The Hydrophyllaceae are a family primarily located in western North America and western South America, from Arctic Alaska south through to southern Patagonia. They are especially common in drier areas of southwestern North America. While less common, they can also be found in eastern North America, but not eastern South America. The Hydrophyllaceae are not naturally found outside of the Americas but the Phacelia have been introduced to parts of Europe and Asia.

Distribution of Hydrophyllaceae in the Americas

Canadian Genera Include:

Ellisia monospecific NAM endemic native from BC east to ON; Hesperochiron 1 W NAM endemic sp. native to BC; Hydrophyllum 5 NAM endemics native to S Canada excluding SK and the maritime provinces; Nemophila 3 former NAM endemics native to BC and AB; Phacelia 13 spp. native to most of Canada except NU, QC, and the maritime provinces; Romanzoffia 2 W NAM endemics native to BC and AB.

USA Genera Include:

Draperia monospecific endemic of CA; Ellisia monospecific NAM endemic, and native to most of the central and eastern USA; Emmenanthe monospecific NAM endemic native CA, NV, UT, and AZ; Eucrypta 2 S NAM endemic spp. native to CA, NV, UT, AZ, NM, and TX; Hesperochiron 1 W NAM endemic sp. native to the western half of the US, E to MN, CO, and AZ; Howellanthus monospecific NAM endemic native to CA (Syn. of Phacelia?); Hydrophyllum 10 NAM endemics native to all of the continental states except for ME, TX, and FL; Nemophila 11 former NAM endemics native to most of the W USA and the SE USA; Phacelia 172 spp. native to all of the USA except FL; Pholistoma 3 S NAM endemics native to OR, CA, NV, and AZ; Romanzoffia 5 NAM endemics native to WA, ID, MT, OR, and CA; Tricardia monspecific USA endemic of CA, NV, UT, and AZ.

Mexico Genera Include:

Emmenanthe monospecific NAM endemic native to NW Mexico; Eucrypta 2 S NAM endemic spp. native to NW Mexico; Hesperochiron 1 W NAM endemic sp. native to NW Mexico; Nemophila 1? sp. NAM endemics native to NW Mexico; Phacelia many, ~100?? spp. native throughout Mexico; Pholistoma 3 S NAM endemic spp. native to NW Mexico.

Neotropical Genera Include:

Phacelia ~9 spp. native to Guatemala, Argentina, Bolivia, Peru, Uruguay, and Chile.

Patagonia Genera Include:

Phacelia ~5-7 spp. native throughout the Patagonia region.

Additional Information and References

• Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
• Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, along with my own personal observations throughout North America.
• Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
• FNA (1993+). Flora of North America. https://floranorthamerica.org/Main_Page. Accessed 2022-current.
• GBIF.org (2020+), GBIF Home Page. Available from: https://www.gbif.org
• iNaturalist.org (2020+). https://www.inaturalist.org/. Accessed 2020-current.
• Luebert, F., Cecchi, L., Frohlich, M. W., Gottschling, M., Guilliams, C. M., Hasenstab-Lehman, K. E., Hilger, H. H., Miller, J. S., Mittelbach, M., Nazaire, M., Nepi, M., Nocentini, D., Ober, D., Olmstead, R. G., Selvi, F., Simpson, M. G., Sutorý, K., Valdés, B., Walden, G. K., & Weigend, M. (2016). Familial Classification of the Boraginales. axon, 65(3), 502–522. https://plants.sdsu.edu/amsinckiinae/pdfs/Luebert_etal2016-Boraginales.pdf.
• ‌Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
• Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. (2009+). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
• Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
• POWO (2019+). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/
• Stevens, P. F. (2001+). Angiosperm Phylogeny Website. Version 14, July 2017 [more or less continuously updated since]. http://www.mobot.org/MOBOT/research/APweb/
• USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; Accessed 2020-present.
• Walden, Genevieve K., Robert W. Patterson & Richard R. Halse. (2023), Hydrophyllaceae, in Jepson Flora Project (eds.) Jepson eFlora, Revision 12, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=157, accessed on April 25, 2026.
• Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
• WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

My Current Plant Family Education Fundraiser

I am currently seeking funding to expand my website and SEO capabilities as I keep adding new families, and I am also looking to invest in a new macro lens, as I will soon be adding floral dissections to the families as they become available to me. You can donate to help support native plant education using the GoFundMe link, also at the bottom of the page.

Copyright Information

The information and the photos on this site are free to use for educational purposes, with proper attribution. For other uses, please contact me first.

You can cite this site as follows: Willis, Lyrae (2020+). Lyrae’s Nature Blog – Plant Families of North America. https://lyraenatureblog.com/. Accessed [Enter Date].