Harrisia fragrans differs from the Caribbean H. eriophora (Pfeiffer) Britton in fruit color (orange-red versus yellow), stem ribbing (10-12 versus 8-9), and spine number and morphology (9-13 per areole, 2-3 cm long, yellow tipped versus 6-9 per areole, 2.5-4.5 cm long, black tipped, respectively). L. D. Benson (1982) recognized these differences but included both taxa within a relatively broad species concept, emphasizing their copious production of long hairs in the flower areoles and other features.
D. F. Austin (1984) reported that the range of Harrisia fragrans is restricted to a 0.5-1.5 kilometer strip in St. Lucie County, Florida, in the immediate vicinity of the original (type) locality. He noted that other populations identified as this taxon actually are "Cereus gracilis," which is presumably H. simpsonii.
Harrisia fragrans is in the Center for Plant Conservation’s National Collection of Endangered Plants.
Harrisia fragrans is a thin columnar cactus that grows on shell mounds and sandy scrub along the Atlantic Coastal Ridge of Florida's east coast from Volusia County south to St. Lucie County (Moore 2012). The columns can be up to 15 feet long, and usually recline against other vegetation when the get that tall. More typically, columns are between 3-7 feet tall and may occur in a small clusters in hammock vegetation. A few columns lay directly on the ground and can give rise to several new vegetative sprouts. The columns have 10-12 ribs, with moderate to deep grooves between. Areolas have a cluster of 9-13 spines with one spine particularly long in each cluster in larger individuals.
Because of the elevated and well-drained nature of the Atlantic Coastal Ridge, major transportation corridors (Florida East Coast railroad, US Route 1, Interstate 95) have encouraged development in habitat formerly occupied by H. fragrans. Because of encroaching development, H. fragrans has been reduced to a few protected areas and immediately adjacent private properties. The vast majority of individuals still in the wild are found in and around Savannas Preserve State Park. Small populations can also be found in Canaveral National Seashore. Almost all other populations between those two sites have been exterminated. The reduced number of individuals (<4000 total) and reduced spatial extent has resulted in this species' listing as federally endangered (USFWS 2010).
Harrisia fragrans is a rare species of cactus known by the common name fragrant prickly apple. It is endemic to Florida, where it is known only from St. Lucie County. The plant's habitat has been almost completely consumed by development, leading to its rarity. It is a federally listed endangered species of the United States.
This is an erect or spreading cactus with narrow, long stems which can well exceed one meter in length, at times approaching five meters.[2][3] It is covered in long, yellow or yellow-tipped spines which may be up to 4 centimeters long.[3] It produces enormous tubular flowers up to 20 centimeters long which are sweet-scented and white to pinkish in color.[3] They bloom at night. The fruit is spherical and red or orange in color, measuring up to 6 centimeters wide. The fruits are a favorite food of local birds,[3] which likely help to disperse the seeds.[4] The cactus has been noted to live at least 19 years, and in general has low fecundity; older, larger plants are more likely to survive, and they have higher fecundity, as well.[4] Small plants may benefit from growing with nurse plants.[5]
The plant's favored natural habitat is mostly coastal hammocks with some shade, as the cactus can become desiccated in full sun.[4] Coastal hammocks of this kind have become uncommon as they have been cleared for development and heavily fragmented.[4]
There are ten confirmed occurrences of the plant, nine of which occur around Savannahs Preserve State Park in St. Lucie County and totalled 2150 individuals in the year 2002.[4] The tenth confirmed occurrence is at the Canaveral National Seashore in Volusia County, and it contains about 96 plants.[4] An occurrence has been reported in Indian River County, but it has not been confirmed.[4] The cactus once grew in at least two places in Brevard County, but these populations have been extirpated.[4]
Remaining populations of the cactus can now be found in sandy scrub habitat.[4] The remaining habitat is degraded with the overgrowth of invasive plant species such as love vine (Cassytha filiformis).[4] While the cactus does not like full sun, it also cannot tolerate being shaded out by brush.[4] Other threats to the plant have been all-terrain vehicles, herbicides, feral pigs, and hurricane damage from wind and falling branches.[4] Populations have been vandalized with machetes.[4] Cacti have died from being buried in sand, and have been stolen by cactus enthusiasts and collectors.[4] A scale insect (Diaspis echinocacti), sometimes eats the stems of the cactus, and some sort of caterpillar has been noted to inflict some damage.[4] Woodpeckers have been observed poking holes in the stems, which injures the plants.[5] Most of the remaining populations are within the bounds of a state park, so their habitat is safe from development.[4]
Harrisia fragrans is a rare species of cactus known by the common name fragrant prickly apple. It is endemic to Florida, where it is known only from St. Lucie County. The plant's habitat has been almost completely consumed by development, leading to its rarity. It is a federally listed endangered species of the United States.
