Pacific Plant Promotions: Passiflora parritae

Passiflora parritae at the author’s home in Richmond, California. Author’s photographs

Passiflora parritae at the author’s home in Richmond, California. Author’s photographs

The genus Passiflora contains 465 species and five subspecies, as listed by the Passiflora Society International. Few rival the size and beauty of Passiflora parritae; its six-inch (occasionally ten-inch) pendant, glowing orange flowers hang on long pedicels for many days before and after flowering, resembling tennis-ball-sized pumpkins. This passionflower is placed by botanists in the subgenus Tacsonia, which includes many other species grown for their generous floral displays, such as the well-known P. mixta and P. mollissima from South America and P. membranacea from Mexico. These are all predominantly cloud forest species that grow in cool but frost-free climates. All of these passionflowers thrive in the fog belt of San Francisco, and beautiful specimens can be enjoyed at Strybing Arboretum and Botanical Gardens in foggy Golden Gate Park.

Passiflora parritae was named for Señor Parra (better known as “Parrita”) who first brought collected specimens to the attention of botanists. It was named by MT Masters in 1882 as Tacsonia parritae and was transferred to the genus Passiflora by Liberty Hyde Bailey in l916. No records can be found of its cultivation before the current plants became available in the l980s, although it is listed in the l922 edition of Bailey’s Standard Cyclopedia of Horticulture. However, a l968 revision of the Passiflora section of Bailey does not list it. The original description notes that it is rare in the wild, and that it grows at elevations between 2,000 and 2,600 meters (6,600 to 8,600 feet) in the Cordillera Central of the Colombian Andes. There remains the possibility that it is in cultivation in some remote garden in its native country, but it is decidedly rare in cultivation elsewhere.

The single plant of Passifora parritae now growing at Strybing was brought into the United States in the mid-1980s by John MacDougal of the Missouri Botanical Garden. He received it as a small seedling from the late Dr Linda Escobar, a botanist at the Universidad de Antioquia in Medellin, Colombia. Dr Escobar had found a mature specimen of the plant in the wild, and her undergraduate students had collected three seedlings; later, a few more plants were found. MacDougal took one of the seedlings home to St Louis; the other two remained in Dr Escobar’s collection but died after failed attempts at tissue culture. The heat of the Missouri summers proved too much for P. parritae, and it barely survived the next two years, according to MacDougal. He recorded only a few inches of growth each year, occurring in spring and fall when the weather was just right; after three years, the seedling was scarcely three feet tall. In the late 1980s, MacDougal sent his plant to fellow passionflower enthusiast John Couch, a former volunteer in Strybing’s nursery, hoping San Francisco’s cool climate would be more suitable for its cultivation. This vine is particular about temperature ranges; apparently, the temperatures in San Francisco’s maritime mediterranean climate closely approximate those in its mountainous Colombian home, because it has, indeed, thrived at Strybing.

Passiflora parritae

Passiflora parritae

Couch distributed rooted cuttings throughout California but recently expressed doubts that any have survived. A few plants were offered at Strybing plant sales at the time. One planted in San Francisco’s warmer Mission District eventually grew to the top of the north wall of a three-story Victorian home and bloomed profusely; it evidently no longer exists. The original stock plant remained in a five-gallon container and survived the big freeze (25° F) of 1990. The heavy leaf cover over the passion vine containers protected the root ball, and it re-sprouted the next summer. It was planted in the gardens in 1994 and bloomed five years later. Rooted cuttings have again been distributed widely to other institutions, including the National Passiflora Collection in England, where they are reportedly growing well. Plants in containers in Southern California are also doing well, although they cease growth in the heat of summer. One rooted cutting planted six years ago in a private garden in the lowlands of West Berkeley, on the eastern side of San Francisco Bay, has grown quite large (thirty feet by twenty feet), flowering profusely for the last three years.

The flowering period runs from late May until September with the heaviest bloom in June and July. Flower buds develop slowly, turning orange at about ping-pong-ball size. Then, over a few weeks, they reach tennis ball size, open for one day, close, and remain on the plant for a few more days. If fruits develop, they stay on indefinitely but turn brown. So far, none of the fruits produced by Strybing’s plant have held viable seed. In July 2003, when the temperature hit 95° F for three consecutive days, all of the developing buds fell off. When cooler temperatures returned, a new crop of flower buds developed. This species does not seem to mind consistent nighttime winter temperatures in the low 30s F. Our best estimate is that the plant should grow where the temperature range rarely exceeds 30° to 90° F. It should really thrive under cool maritime conditions along the California coast, where freezes are rare. It is apparently not particular about soils or fertilizer. Its ecological amplitude is not truly known, and it may be adaptable to much wider conditions. It has been difficult to propagate, although cuttings taken during the active growing period root well if not given too much bottom heat. Pacific Horticulture readers who experiment with Passiflora parritae will truly be the ones to write the story of this rare plant.