Hesperoyucca is a small genus of three species of flowering plant

Flowering plant

The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

s closely related to, and recently split from, Yucca

Yucca

Yucca is a genus of perennial shrubs and trees in the family Asparagaceae, subfamily Agavoideae. Its 40-50 species are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal panicles of white or whitish flowers. They are native to the hot and dry parts of North...

, which is in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Asparagaceae

Asparagaceae

Asparagaceae is the botanical name of a family of flowering plants, placed in the order Asparagales of the monocots.In earlier classification systems, the species involved were often treated as belonging to the family Liliaceae...

, subfamily Agavoideae.

Description

Hesperoyucca is distinct from Yucca in having dehiscent fruit

Fruit

In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 and a scape more than 2.5 cm diameter with reflexed (not erect) bracts. The stigma

Stigma (botany)

The stigma is the receptive tip of a carpel, or of several fused carpels, in the gynoecium of a flower. The stigma receives pollen at pollination and it is on the stigma that the pollen grain germinates. The stigma is adapted to catch and trap pollen with various hairs, flaps, or sculpturings...

 is capitate, whereas those of Yucca split into three reflexed lobes. The glutinous pollen

Pollen

Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...

 is released in a sticky mass; that of Yucca species is released as single grains. Hesperoyucca is also distinct in DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 analysis. The genus is native to Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 and the southwestern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Species

• Hesperoyucca newberryi (syn. H. whipplei subsp. newberryi, Yucca newberryi )
• Hesperoyucca peninsularis
• Hesperoyucca whipplei (syn. Yucca whipplei ) – chapparal yucca, our Lord's candle or Spanish bayonet.

Taxonomy

The taxonomy of Hesperoyucca is complex and somewhat controversial. Originally, in 1871, George Engelmann

George Engelmann

George Engelmann, also known as Georg Engelmann, was a German-American botanist. He was instrumental in describing the flora of the west of North America, then very poorly-known; he was particularly active in the Rocky Mountains and northern Mexico.-Origins:George Engelmann was born in Frankfurt...

 ranked "Hespero-Yucca" as a section

Section (botany)

In botany, a section is a taxonomic rank below the genus, but above the species. The subgenus, if present, is higher than the section, and the rank of series, if present, is below the section. Sections are typically used to help organise very large genera, which may have hundreds of species...

 of Yucca (with only one member, Yucca whipplei; all other Yucca species he placed in section Eu-Yucca, with three subgroups). In 1895 he revised his classification of Yucca, to four equal groups, of which Hesperoyucca was one. In 1876, John Gilbert Baker

John Gilbert Baker

John Gilbert Baker was an English botanist.Baker was born in Guisborough, the son of John and Mary Baker and educated at Quaker schools in Ackworth and York....

 gave it the rank of subgenus

Subgenus

In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...

; in 1892 he noted that it "had better be kept as a genus distinct from Yucca" (but actually retained the name Y. whippleii [sic]).

Some authorities accept this as having erected the genus Hesperoyucca, but others credit this to William Trelease

William Trelease

William Trelease was an American botanist, entomologist, explorer, writer and educator. This botanist is denoted by the author abbreviation Trel. when citing a botanical name....

, who printed a taxonomic description in 1893, formally recognising Hesperoyucca as being at the same rank as, but separate from, Yucca. It has taken recent DNA analysis to confirm that they are indeed genetically distinct from Yucca.

The splitting of Hesperoyucca from Yucca is still not widely reflected in available literature or online (for example, the British Royal Botanic Gardens, Kew and the Royal Horticultural Society

Royal Horticultural Society

The Royal Horticultural Society was founded in 1804 in London, England as the Horticultural Society of London, and gained its present name in a Royal Charter granted in 1861 by Prince Albert...

websites do not recognise the name as current).