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Family: Brassicaceae (Mustard family)
Mid-Atlantic bloom time:
March - May
Mid-Atlantic fruit ripe:
April - May
Identification Caution: Spring Cress (Cardamine bulbosa) and Purple Cress (Cardamine douglassii) are often nearly impossible to differentiate in the field. Many of their defining characteristics overlap, further complicated by them hybridizing in locations where they both can grow. Perhaps the most quoted source for their identification is a 1976 paper by Hart and Eshbaughi in the Journal of the New England Botanical Club1.
The identification characters most often used to separate the two species are:
| feature | C. bulbosa | C. douglassii |
| rhizomes | short, erect or horizontal, barely subterranean, stout, knotty or tuberous, white | sometimes surficial and becoming green |
| stems | 15–60 cm,erect, simple or with a few upper branches, glabrous, or with hairs < 0.1 mm long | 10–50 cm, erect, pubescent (with hairs (0.2–) 0.3–0.6 (–0.8) mm long), with the lower portion cinereous (ash-colored) |
| basal leaves | blades 2.5–8 cm, oval or rotund to reniform, entire or repand, rarely purplish beneath, deciduous before anthesis | to 3 cm, orbicular or nearly so, purplish beneath, especially when in full sun, petiolate |
| cauline leaves | 4–12, scattered, ovate or narrowly oblong to elliptic or lanceolate, serrate or entire and undulate | 2–5, smaller, ovate to oblong |
| petioles | to 9 cm on basal leaves, reduced progressively upward to lacking | lowermost 2 cauline leaves sometimes petiolate, otherwise petioles lacking |
| pedicels | to 4 cm, ascending to divergent | lowermost pedicels 1.5–4 cm, divaricately ascending |
| sepals | 2.5–5 mm | 3–6 mm |
| petals | 7–16 mm, white, or rarely, pink | 7–20 mm, pink to lavender or, rarely, white |
| siliques | 15–30 x to 1.5 mm, plus a beak 2–3 mm | 10–20 x 1–2 mm, plus a beak 2–4 mm |
| seeds | to 2.5 mm, dark brown | to 1.5 mm, dark brown |
| bloom/fruit | Mar–May; Apr–May | Mar–Apr; Apr–May |
The specimens shown here represent my best guess as to them being Spring Cress (C. bulbosa), because their:
- upper stems are glabrous
- sepals are glabrous
- near-basal leaves are repand
- flowers are all white or nearly so
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1 April 2022
Bristow, Prince William County, VA (note the overall white color of the blooms) 
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1 April 2022
Bristow, Prince William County, VA (note the the glabrous stem and green sepals) 
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1 April 2022
Bristow, Prince William County, VA (note the wavy edges of the leaves) 
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1 April 2022
Bristow, Prince William County, VA (underside of leaf fully exposed to sunlight only slightly purple) 
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1 April 2022
Bristow, Prince William County, VA (note the the glabrous stem and sepals) 
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1 April 2022
Bristow, Prince William County, VA (note the the glabrous stem and sepals) 
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References