Grapefruit

Oroblanco is a pummelo–grapefruit hybrid developed at UCR. Its large, nearly seedless fruit is unusually sweet and mild, with low acidity and much less bitterness than standard grapefruit. It also needs less heat to develop good quality, making it especially useful in cooler coastal and mild inland parts of California where conventional grapefruit may disappoint.

Cocktail “Grapefruit” is not actually a grapefruit, but a UC Riverside hybrid of Siamese Sweet pummelo and Frua mandarin. It was never formally released by UCR, but escaped from the breeding program and became popular with California home growers and farmers-market producers and is often labeled as a grapefruit by nurseries. The unusual fruit combines the sweetness of a low-acid pummelo with the flavor and juiciness of a mandarin.

Melogold is a UC Riverside pummelo–grapefruit hybrid and a sibling of Oroblanco, but with larger fruit and a somewhat more grapefruit-like character. It combines the sweetness and low acidity of its pummelo parent with juicy, seedless to nearly seedless flesh. Its lower heat requirement than traditional grapefruit makes it especially useful for California growers outside the hottest inland areas.

Chironja is an unusual Puerto Rican citrus traditionally regarded as a natural sweet orange–grapefruit hybrid, though its exact parentage remains uncertain. The fruit is large, juicy, and notably sweeter and less bitter than typical grapefruit, with a flavor that leans strongly toward orange. Its obscure Caribbean origin and distinctive taste make it especially appealing to collectors.

New Zealand Grapefruit, also called Poorman Orange, is not a true grapefruit but an old pummelo-type hybrid that became the standard “grapefruit” of New Zealand because it can ripen where true grapefruit lacks enough heat. The fruit is juicy, sweet-tart, and mildly bitter, with orange-yellow flesh and numerous seeds. Its cool-climate adaptability makes it especially interesting for California growers near the coast.

Wekiwa is an unusual historic “tangelolo,” a grapefruit × Sampson tangelo hybrid—making it roughly three-quarters grapefruit by pedigree. Its small, juicy fruit is sweet and mildly tart, with pale yellow rind that can develop a pink blush and amber-pink flesh under favorable conditions. Early ripening from November to January at Riverside, it is a distinctive collector’s grapefruit hybrid rather than a typical tangelo.

Flame is a Florida grapefruit bred for deep red color without the fussiness of Star Ruby. Its flesh can approach Star Ruby in intensity, but the tree is more vigorous and better able to handle cold. For home growers who want a striking red grapefruit with fewer cultural headaches, Flame offers an unusually good balance of appearance, performance, and eating quality.

Rio Red is the standard red grapefruit of the Texas industry, bred at the Texas A&M Citrus Center from irradiated budwood and released in 1984. Its deep red, nearly seedless flesh holds color far better than the older Ruby Red types, and fruit keeps sweetening on the tree from winter into spring. Rio Red is a true grapefruit with a high heat requirement — expect excellent fruit in the Central Valley and hot inland yards, but thin, tart fruit near the coast.

Redblush, also known as Ruby Red, is the grapefruit that brought deep pink-red flesh into the mainstream. Discovered in Texas as a mutation of Thompson, it became one of the foundational red grapefruit cultivars and helped set the direction for the deeper-red varieties that followed. For a home grower, its appeal is historical as much as horticultural: this is one of the varieties that changed what people expect a grapefruit to look like.

Shambar is California's own grapefruit — a bud sport of Marsh found in a Corona orchard in 1936 and sold commercially from 1945, but never widely planted. The fruit is seedless, with attractive salmon-colored flesh and typical pigmented grapefruit flavor, and may ripen slightly ahead of Marsh. Its reputation for deeper color is shaky: UCR evaluators at Lindcove found it essentially identical to Redblush. Like any true grapefruit, it needs hot inland summers to sweeten.

Star Ruby came out of R. A. Hensz's Texas breeding program from irradiated Hudson grapefruit seed, and it still has the darkest flesh of any pigmented grapefruit — deep red, juicy and nearly seedless under a smooth, blushed rind. It is also the fussiest: less vigorous than other grapefruit, with smaller fruit and more trouble from phytophthora, nutrient deficiencies, cold and pests. Not a beginner's grapefruit, but nothing else comes close on color.

Henderson Ruby is a Texas grapefruit discovered in the early 1970s as a limb mutation of an older red grapefruit tree. It was an important step beyond Ruby Red, producing much deeper red flesh and stronger rind blush while holding its color later into the season. The fruit is commercially seedless and of excellent eating quality, making it an appealing choice for growers who want a classic Texas-style red grapefruit.

Croxton is a rare South Carolina grapefruit grown from seed by Richard Croxton in Columbia and later preserved and promoted by longtime citrus collector Hershell, who has called it his favorite grapefruit. The original tree became known for thriving well outside the usual grapefruit belt. Its backyard origin, Southern hardiness, and endorsement by an experienced collector give Croxton an unusually compelling story.

Ray Ruby is a Texas red grapefruit discovered as a natural mutation in Weslaco in 1970. Its appeal is classic Rio Grande Valley grapefruit character: richly colored flesh, strong sweet-tart flavor, and best quality in substantial summer heat. For growers in hot inland California, it offers a distinctly Texas-style red grapefruit that rewards the right climate.

US HoneyCoat began in 1973 when USDA breeder C.J. Hearn irradiated Foster grapefruit, then spent decades moving through selection and regeneration before its 2018 release. The result is a pink grapefruit that keeps classic grapefruit character but with far fewer seeds, lower acidity and bitterness, and earlier maturity. Its long path from mutation experiment to named cultivar makes it one of the more unusual modern USDA grapefruits.

Duncan is one of the oldest named grapefruit cultivars in America, tracing to a tree growing near Safety Harbor, Florida by about 1830. Long before seedless grapefruit took over the market, Duncan was prized for its rich, intense flavor and became a benchmark for grapefruit quality. It is very seedy, but for collectors its historical importance, vigorous growth, and reputation for unusual cold toughness make it a true heritage variety.

Frost Marsh is essentially a “cleaned-up” Marsh grapefruit: a nucellar seedling raised by UC Riverside’s H.B. Frost from Marsh seed planted in 1916 and released commercially in 1952. It became the principal Marsh clone propagated in California. For collectors, its appeal is less novelty of flavor than pedigree—it is a living piece of California citrus-improvement history, carrying classic Marsh character in a selected UC line.

J.F. Reed of Taft, California planted seeds from grapefruit bought at a grocery store, and one seedling proved good enough to preserve. UCR later found the fruit essentially identical to Marsh, but Reed’s appeal is its accidental backyard origin—a reminder that an ordinary grocery-store seed once produced a selection worthy of the Citrus Variety Collection.

Brown Marsh is a name historically associated with the classic Marsh seedless grapefruit, and authoritative citrus references list it as a synonym of Marsh. Marsh transformed the grapefruit industry after its discovery in Florida in the 1800s, eventually becoming the world’s dominant grapefruit and giving rise to Thompson, Redblush, and much of the modern red-grapefruit lineage.

Genetic Dwarf Grapefruit is a limb sport of Marsh discovered in Yuma, Arizona and brought to UC Riverside in the 1960s. The name is misleading: “dwarf” refers mainly to its shorter internodes, smaller leaves, and denser growth, not to a truly dwarf tree. It can still approach normal grapefruit size at maturity, so buyers should expect a somewhat more compact Marsh—not a patio-sized tree.