Two Susans occur along the GAP:
Black-eyed Susan (Rudbeckia hirta)
Botanical Classification
- Scientific name: Rudbeckia hirta
- Family: Asteraceae (Aster/Sunflower family)
- Life cycle: Biennial or short-lived perennial (sometimes behaves as annual)
Physical Characteristics
Size:
- Height: 2-4 feet (60-120 cm)
- Spread: 1-2 feet (30-60 cm)
Flowers:
- Size: Large—2.5-4 inches across (6-10 cm)
- Ray petals: Yellow, golden-yellow to orange (8-21 rays)
- Center disk: Dark brown to black, dome-shaped and prominent
- Bloom time: June to October (late summer through fall)
- Fewer but larger flowers per plant
Leaves:
- Basal leaves: 10-18 cm long, mostly unlobed
- Larger leaves overall (3-7 inches long)
- Covered in coarse, stiff hairs giving rough texture[3][1]
- "Hirta" means "hairy" in Latin—referring to the bristly trichomes
Stems:
- Stout, branching, hairy stems[1]
- Usually over 8 inches long[4]
Habitat & Distribution
- Native to eastern and central North America
- Found in all 48 contiguous states and all 10 Canadian provinces
- Grows in prairies, meadows, roadsides, disturbed areas
- Tolerates: Heat, drought, poor soil, wide pH range
- State flower of Maryland
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| Black-eyed Susan |
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| Black-eyed Susan |
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| Black-eyed Susan |
Brown-eyed Susan (Rudbeckia triloba)
Botanical Classification
- Scientific name: Rudbeckia triloba
- Family: Asteraceae (Aster/Sunflower family)
- Common names: Brown-eyed Susan, three-lobed coneflower, thin-leaved coneflower, branched coneflower
- Life cycle: Biennial or short-lived perennial
Physical Characteristics
Size:
- Height: Taller—2-5 feet (can reach up to 5 feet
- Spread: 1-1.5 feet (narrower than black-eyed
- Bushy, open, branched appearance
Flowers:
- Size: Smaller—1-2 inches across (about 1/3 the size of black-eyed)
- Ray petals: Deep golden yellow, 6-13 shorter, wider rays
- Center disk: Dark purple-brown to jet-black, button-shaped, flattened cone (slightly lighter than black-eyed)
- Bloom time: Later season—late summer through fall (July-October), until hard frost
- More numerous flowers covering the entire plan
- Longer blooming period
Leaves:
- Distinctive three-lobed basal leaves (hence "triloba")
- Upper leaves: Smaller, lance-shaped, often unlobed
- Thinner, more delicate leaves than black-eyed
- 2-4 inches long, ½-2 inches wide
- Covered in bristly hairs but less coarse than black-eye
Stems:
- Many-branched stems creating masses of flowers
- Bristly hairy, often reddish-green
- "Country cousin" appearance—more sprawling
Habitat & Distribution
- Native to eastern and central United States (New York to Florida, west to Minnesota, Utah, Texas)
- Prairies, woodland borders, thickets, rocky slopes, roadsides
- Prefers moist soil but adaptable
- Hardy zones 3-10 (very adaptable)
How to Tell Them Apart in the Field
Quick Visual Cues:
1. Flower size is the giveaway
- If the bloom is as big as your palm → Black-eyed Susan
- If the bloom is 1/3 that size → Brown-eyed Susan
2. Look at the leaves
- Large, hairy, mostly unlobed → Black-eyed Susan
- Three-lobed basal leaves, thinner overall → Brown-eyed Susan
3. Count the flowers
- A few big, bold flowers → Black-eyed Susan
- Plant covered in masses of smaller flowers → Brown-eyed Susan
4. Growth habit
- Sturdy, upright, well-behaved → Black-eyed Susan
- Bushy, branching, sprawling → Brown-eyed Susan
Ecological & Garden Value
Both species are outstanding for:
- Naturalized plantings and meadows
- Pollinator gardens
- Native plant gardens
- Cottage gardens (especially brown-eyed)
- Roadsides and disturbed areas
- Prairie restoration
- Butterfly gardens
- Cut flower gardens
Historical/Medical Note: Native Americans used Rudbeckia hirta medicinally, though the plant is toxic to cats. Both species have been used in folk medicine.
Along the GAP
Given that the Great Allegheny Passage runs through prime habitat for both species—disturbed roadsides, woodland edges, open meadows, old fields—you'll encounter both along your journey.
Look for:
- Black-eyed Susan (R. hirta) in sunnier, more open areas with those big, bold 3-4 inch flowers
- Brown-eyed Susan (R. triloba) in slightly shadier woodland borders and thickets, creating clouds of smaller blooms in late summer
Both are quintessential late-summer sights along the GAP—cheerful yellow beacons that brighten the landscape just as other wildflowers are fading into autumn.
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| Brown-eyed Susan |
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| Brown-eyed Susan |
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| Brown-eyed Susan |
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| Brown-eyed Susan |
