The True Spring Ephemerals in Nova Scotia

Panel photo by Patrick Foote

Five of the "true" spring ephemeral species are found in
the rich hardwood forests & intervales of Nova Scotia

Photo-essay by JackPine (NSWFS)
Posted 4 Apr. 2012
Update 6 June 2016

The "true" spring ephemerals

The "spring ephmeral" label is often applied rather loosely to all herbaceous species in eastern hardwood forests that flower before the tree canopy closes. It applies more properly to a "temporal guild" of herbaceous perennials that "emerge and senesce prior to canopy closure",¹ i.e., whose above-ground parts, at least, are ephemeral.

These species have a small window of sunshine between snowmelt and leaf-out in which to grow, flower, be pollinated, and produce seeds. By mid-June the deciduous trees that tower above have cloaked the forest floor in deep shade. Spring ephemerals disappear in the heat of the summer, retreating underground until next year.²

Sometimes this group is referred to as "the true spring ephemerals" to make the distinction from the more loosely applied term. The garden equivalents are the crocusses, daffodils, snowdrops, tulips and the like, which give us the first colour in spring but do not usurp the space for the summer flowers. They are all exotic to North America.

By my count, Nova Scotia has five species amongst the dozen or so cited in scientific papers as belonging to the spring ephemeral guild for the hardwood forests of eastern North America³:

Allium tricoccum (wild leek) - flowers in July, after vegetative growth has died back
Claytonia caroliniana (spring beauty) - flowers May 15 to early June
Cardamine diphylla (toothwort) - flowers April to early June
Dicentra cucullaria (Dutchman's breeches) - flowers May 20 to June 10
Erythronium americanum (trout lily) - flowers early May

Flowering times are those for Nova Scotia.⁴ Missing from the flower photos: Allium tricoccum (wild leek). Please tread carefully if you know where to find it - it is red listed (S1).⁵

Click on photos for larger versions/more photos.

More photos of spring ephemerals in Nova Scotia would be welcomed. Comments too!⁶

"They remind me of playing outside as a child, discovering magical scenes where boulders blanketed in lush green mosses rest beneath as yet unleafed oak and maple trees, and the most delicate wildflowers glow in narrow sunlight." - Janis Cormier

Claytonia caroliniana (spring beauty)
at Cape Split, N.S. May 19, 2008

Dicentra cucullaria (Dutchman's breeches)
at Cape Split, N.S. May 18, 2008

Wild leek at Cape Blomidon, May 28, 2015.
Flowers expected in late July

Cardamine diphylla (toothwort)
on Meander River, N.S.,
May 19, 2011

Erythronium americanum (trout lily)
by road at White Rock, N.S.
May 4th, 2011, photo by Patrick Foote.

Some features of the spring ephemerals:⁷

they occur mostly on richer soils in hardwood forests* that are heavily shaded through the summer;
all are perennials, sprouting from bulbs or bulb-like structures;
they are relatively short (as they have no need to compete with taller plants) with basal leaves or "short umbrellas" of leaves;
they exhibit high rates of photosynthesis in the open canopies which requires high levels of leaf nutrients, a factor which tends to restrict them to richer soils;
they senesce prior to canopy closure and go dormant during the summer;
roots and shoots begin to grow slowly over the fall and winter;
bumble bees (Bombus spp) are important pollinators for some species, notably Dutchman's breeches; other pollinators include solitary bees, flies and to a lesser extent butterflies and skippers;
ant dispersal of seeds is important for several or more species;
the guild appears in forests of eastern Asia (Japan, parts of Russia, China), but is absent from the forests of Europe;
the spring ephmerals are sensitive to human disturbance and were likely much more abundant in the pre-Europen forests.

* From Keddy⁸: The Rich Hardwood Forest Flora… is probably best developed in the central regions of N.S., although fine hardwood valleys also can be found in northern Cape Breton. Deciduous tree species such as sugar maple (Acer saccharum) and beech (Fagus grandifolia) characterize these rich hardwood areas. Valleys and river banks tend to have the richest soil, and it is in these wet areas - often termed "intervales" - that the greatest number of hardwood forest species can be found. It was also these areas which were originally cleared for agriculture. Today, only a few scattered pockets of undisturbed rich intervale habitat survive. In these few areas, rare or threatened species such as Wild Leek (Allumim tricoccum), Blue Cohosh (Caulophyllus thalictroides ), Canada Lily (Lilium canadense) and Hepatica (Hepatica americana) still persist.

The Early Summer Forbs

Many more species belong to the temporal guild of "early summer forbs" or "summer greens" that emerge in spring and persist through canopy closure for varying lengths of time but reach peak coverage before mid summer. ¹ As a group, these species grow to taller heights and encompass a wider range of growth forms and habitats than the spring ephemerals.⁹ Examples of the early summer species in the hardwood and mixed forests of Nova Scotia:

Aralia nudicaulis (wild sasparilla) - flowers May to July
Anemone quinquefolia (wood anemone) - flowers late May to early June
Arisaema triphyllum (Jack in the pulpit) - flowers mid May to early July)
Caulophyllum thalictroides (blue cohosh) - flowers beg. of June
Clintonia borealis (bluebead lily, corn lily) - flowers beg. of June
Maianthemum canadense (wild lily of the valley) - flowers late May & June
Rubus pubescens (dwarf raspberry) - flowers early June
Sanguinaria canadensis (bloodroot) - flowers early May
Smilicina racemosa (false solomon's seal) - flowers early June
Streptopus roseus (rosy twisted stalk) - flowers Late May/June
Tiarella cordifolia (false miterwort) - flowers May 15 to June 15
Trientalis borealis (starflower) - flowers May to Aug.
Trillium erectum (purple trillium) - flowers late May/early June
Viola pubescens (yellow violet) - flowers April to May

The term "vernal forbs" (or "vernal herbs") has been used to refer to spring ephemerals plus early summer forbs, as defined above, or defined more simply as spring-flowering herbs.

Some might ask whether Hepatica nobilis, one of the NSWFS favourites, fits in this scheme. Hepatica flowers early, but its leaves persist until the next spring bloom. Thus it is clearly not a spring ephemeral and because its leaves persist over winter, it differs from the early spring forbs defined as above. However, it would qualify as a "vernal herb" when that is defined simply as spring flowering herbs. See Hepatica, The Other First Flower of Spring for more about Hepatica.

Aralia nudicaulis, May 25, 2010

Maianthemum canadense, June 5, 2009

Trillium erectum, May 18, 2008

Alliaria petiolata (garlic mustard)
in Victoria Park, Truro, N.S. May 23, 2009

According to CARP, garlic mustard is currently restricted to one known location in the Annapolis Valley. ¹² I first observed the plant in Victoria Park in Truro in 2009 & NSWFS President Charles Cron photographed it at the same site in 2000. So evidently it occurs in other locales and we need to look out for it, May to mid-June are the best times to find it.¹³

Invasive vernal herb: garlic mustard

Garlic mustard (Alliaria petiolata ) is a species of Eurasian origin that invades hardwood forests and outcompetes many of our native vernal herbs. It is a biennial, producing a basal rosette in its first year and flowering shoots in the second year. It is during the second year that it competes significantly with native species. The basal rosettes are capable of high rates of photosynthesis in the early spring while the canopy is open, enabling it to compete with spring ephemerals. Then,

…as the canopy closes and native [early spring and summer ] species begin to increase in cover and height, the elongating shoot of A. petiolata supports shade-adapted leaves at higher levels where they could more effectively compete with native species. Thus, A. petiolata grows in the early spring before most native species are actively growing, and extends its growing season into the summer through stem elongation and production of new leaves that are adapted to ambient irradiance levels unlike native ephemeral species or summer forbs. ¹¹

White-tailed deer are reported to "assist in its spread by eating native plant species that they prefer and are adapted to eat, leaving the garlic mustard behind." Garlic mustard was apparently introduced to North America in the 1800s for culinary and medicinal purposes.¹¹ It is a relatively recent arrival in N.S., and found in only a few locales, so with some vigilance we could likely limit its spread and damage to native herbs.

Glossy and common buckthorns (Rhamnus frangula & Rhamnus cathartica) are also invasive in spring ephemeral habitats in Nova Scotia¹⁴

Conservation of our spring ephemerals

Of our five spring ephemerals, only wild leek is in imminent danger of being lost ("extirpated") from N.S. It is known from only a few locales in northern N.S. and is red listed (conservation status S1). The other four species are all ranked S4/S5. I suspect that that the longer term concern (indicated by S4) relates to the fact that the rich hardwood forests and intervales in which they occur were once widespread and extensive, but now are much smaller and highly fragmented, increasing the likelihood of progressive decline in abundance over longer time frames. These habitats are also under-represented in Nova Scotia's protected areas network.

Add to that, ongoing loss of these areas and threats from invasive species, clearcutting and excessive deer grazing, we should certainly not be complacent about the status of our true spring ephemerals. Hardwood intervales, in particular, are hotspots of plant biodiversity, and include threatened species such as blue cohosh and maidenhair fern, as well as the spring ephemerals. We should never take these gems for granted!

Notes and References

Intervale forest on Meander River, N.S.
May 19, 2011

Posted 4 Apr. 2012. Modified 6 Jun 2016.

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