Yellow Morning Glory

Merremia tuberosa is native to tropical America, from Mexico and the Caribbean south through Central America to Brazil and Bolivia, where it grows in tropical lowland forests, forest edges, and disturbed habitats.

• The genus Merremia is named after Blaise Merrem (1761–1824), a German zoologist and botanist
• The species name tuberosa refers to the tuberous roots that the plant develops
• Also known as "Hawaiian Woodrose" (though it is not from Hawaii), "Yellow Woodrose," and "Arborvine"
• Introduced to Hawaii in the 19th century as an ornamental vine, where it subsequently escaped and became a serious invasive weed
• Has also become invasive in parts of Southeast Asia, tropical Africa, the Pacific Islands, and Florida
• The distinctive woody seed pods are often sold as "wood roses" in the dried flower and craft trade
• The genus Merremia contains approximately 80 species of tropical vines, closely related to Ipomoea
• The plant has been used in traditional medicine in its native range for skin conditions and as a purgative
• Seeds may contain trace amounts of ergoline alkaloids, though much less than Argyreia nervosa
• The plant's aggressive growth and shade tolerance make it a formidable invasive species in tropical forests

Yellow Morning Glory is a large, vigorous evergreen woody vine climbing by twining stems to heights of 10–15+ m, capable of engulfing entire tree canopies in tropical conditions.

Stems: Stout, woody, green to brownish, twining tightly around supports. Young stems are green. Mature stems can become thick and rope-like.

Leaves: Large, palmately lobed to nearly entire, 10–20 cm long and wide, bright green, smooth, with 5–7 shallow to deep lobes. Leaves are arranged alternately and create dense shade beneath the vine.

Flowers: Produced in clusters of 1–3 from the leaf axils. Individual flowers are broadly funnel-shaped (funnelform), 5–7 cm across, bright golden-yellow to lemon-yellow, with 5 shallow lobes and a deeper yellow throat. Flowers open in the early morning and close by midday. Blooms primarily in fall and winter in the tropics.

Fruit: The distinctive feature — large, hard, woody, rounded capsules 3–5 cm in diameter, dark brown, resembling carved wooden roses. Each capsule contains 4 large (1–1.5 cm), dark brown to black seeds. The woody capsules persist on the vine for months and are commonly used in dried flower arrangements.

Roots: Develops tuberous roots that store energy and allow the plant to regrow after damage or drought. The tubers make eradication difficult.

Yellow Morning Glory grows naturally in tropical lowland forests, forest edges, and disturbed habitats throughout tropical America, where it scrambles through the canopy and along forest margins.

• INVASIVE in Hawaii, where it is one of the most problematic forest weeds — it smothers native trees in mesic and wet forests
• Also invasive in parts of Southeast Asia, tropical Africa, Pacific Islands, and southern Florida
• Thrives in full sun to deep shade — the shade tolerance is a key factor in its invasive success
• Tolerates a wide range of soil types and moisture conditions
• The vine grows extremely rapidly — up to 5–8 m per year in tropical conditions
• Forms dense, smothering blankets over tree canopies, blocking photosynthesis and eventually killing host trees
• Dispersed by seeds (wind and water) and by stem fragments that root at nodes
• The woody seed pods float in water and can be dispersed by streams and ocean currents
• In Hawaii, extensive control efforts using herbicide and manual removal have been undertaken at great expense
• Biological control research has investigated insects from the plant's native range in Central America
• In its native tropical America, natural controls keep the plant in balance with the ecosystem

Yellow Morning Glory should NOT be planted in tropical regions where it is invasive. In its native range or in controlled settings, it can be grown for its cheerful yellow flowers.

Control (invasive situations):
Mechanical: Cut vines at accessible heights and pull down from trees. Remove root crowns and tubers where possible. Bag and destroy all seed pods.

Chemical: Cut-stump treatment — cut vines and immediately apply herbicide (glyphosate or triclopyr) to the cut surface. Foliar spray of herbicide can be used on ground-level growth.

Prevention: Do not plant in Hawaii, Southeast Asia, or other tropical regions where the species is known to be invasive. Remove seedlings before they establish.

If Growing (native range only):
Site Selection: Full sun to partial shade. Very sturdy support required.

Soil: Any well-drained soil. Extremely adaptable.

Watering: Drought-tolerant once established. Regular water during establishment.

Pruning: Prune aggressively to control size.

Hardiness: USDA Zones 10–12. No frost tolerance.

Propagation: By seed (scarify and soak before planting) or stem cuttings.

Caution: Do not plant near native forest in tropical regions.