Yellow orchid vine, Butterfly vine

Callaeum macropterum

Callaeum macropterum in July 2025 under low irrigation. The plant is slow growing with some plants forming only a shrub. It did not form a dense canopy over the trellis. Foliage is healthy and blooming occurred throughout the summer and early fall in waves.

Summary

Mascagnia macroptera (Callaeum macropterum) is a perennial vine native to Arizona and Mexico. Plants are suited for USDA hardiness zones 8b to 10 and remain evergreen with temperatures above the mid twenties Fahrenheit Yellow orchid vine has a moderate to fast growth rate expanding to 16 feet high and 20 feet wide. The stems are twining and need support. Leaves are lanceolate, dark green, and up to 2 inches long and 1 inch wide. Yellow flowers with five petals are up to one inch in diameter and resemble orchid flowers. Plants flower from spring through summer. Flowers turn into chartreuse colored winged fruit resembling butterflies and then into brown fruit that persist for several weeks. The plant is considered heat and moderately drought tolerant, but more irrigation during the summer results in more foliage and flowers.

Yellow orchid vine was only grown in Tucson, AZ where it remained evergreen during the study duration. Growth was very slow, with percent trellis cover in April 2025 around 5%. By October only 5% to 25% of the trellis was covered with foliage. Some plants had less of a vining growth habit and instead grew multiple shorter stems from the base, resembling a mounding groundcover rather than a vine. Trellis coverage increased over the growing season with highest values in July and September. Medium irrigation had a higher average trellis cover (13.4 %) than the highest irrigation (9.8 %). Foliage quality was high averaging 4.0 to 4.2 across irrigation treatments. Peak flowering occurred from June to October, with fewer plants flowering and less flower cover in August. Pest and disease resistance were high throughout the season; mortality was very low with one plant dying in 2024 and one in 2025. Overall appearance ranged from 3 to 5; only the low irrigation treatment in August was rated 2.5. Irrigation recommendation for this plant is 20% of ETo. The slow growth rate and bushy growth habit  is a concern if the goal of the vine is to provide shade or a screen in a short period of time.