Question: Which genus has more species, Acanthus or Clematis?
Context: Blepharis dhofarensis is a species of plant in the Acanthaceae family.  It is found in Oman and Yemen.  It is threatened by habitat loss.  Recent molecular work has placed it in the genus "Acanthus" instead. American water-willow (Justicia americana) is a herbaceous, aquatic flowering plant in the Acanthus family native to North America.  It is the hardiest species in the genus "Justicia", the other members of which being largely tropical and subtropical, and it is able to survive as far north as USDA zone 4.  It is common throughout its range. Hygrophila, commonly known as swampweeds, is a genus of flowering plants in the acanthus family, Acanthaceae.  There are about 80 to 100 species, of which many are aquatic plants.  The genus is distributed across the tropical and subtropical world.  It is one of only two genera in its family that contains aquatic plants, the other being "Justicia".  The genus is treated in the tribe "Hygrophileae", which is noted as being in need of revision at the genus level, meaning the current taxonomic boundaries of "Hygrophila" are likely to change in the future. Petalidium, commonly known as petal-bushes, is a genus of perennial shrubs in the acanthus family.  They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands.  The majority of species occur in frost-free, summer rainfall regions of southern Africa, and may be found from low to medium altitudes. Acanthus hirsutus is a plant species in the genus "Acanthus". Over 70 species and cultivars of clematis currently (2016) possess the Royal Horticultural Society's Award of Garden Merit, reflecting this plant's continued popularity in gardens in the United Kingdom.  "Clematis" is a genus of woody based perennials, mostly climbers with a twining habit, though some are grown as groundcover or as herbaceous plants.  They can be evergreen or deciduous.  They bear flowers in all shades except black, pure blue, pure red and orange.  The flowers are often large and showy.  They can be single or double, fragrant or unscented, compact or vigorous, in a wide range of shapes and sizes.  The flowering period varies from early spring to late summer.  Many spring-flowering cultivars produce a second flush of blooms after the main display has finished, and many have attractive silky seed-heads prolonging the period of interest.  Clematis can be grown against walls, fences, over pergolas and obelisks, or through other shrubs and trees. Trichanthera is a monotypic genus of flowering plants in the acanthus family containing the single species Trichanthera gigantea, which is known by many common names, including madre de agua, suiban, cenicero, tuno, naranjillo, and palo de agua.  It is native to Central America and northern South America.  It has also been introduced to other tropical regions such as Vietnam, Cambodia, and the Philippines. Acanthus is a genus of about 30 species of flowering plants in the family Acanthaceae, native to tropical and warm temperate regions, with the highest species diversity in the Mediterranean Basin and Asia.  Common names include Acanthus and Bear's breeches.  The generic name derives from the Greek term for the Acanthus mollis, ἄκανθος , "akanthos", a plant that was commonly imitated in Corinthian capitals. Acanthus mollis, commonly known as bear's breeches, sea dock, bearsfoot or oyster plant, is a herbaceous perennial plant with an underground rhizome in the genus "Acanthus".  It is regarded as an invasive species in some jurisdictions. is a genus of about 300 species within the buttercup family Ranunculaceae.  Their garden hybrids have been popular among gardeners, beginning with "Clematis" × "jackmanii", a garden standby since 1862; more hybrid cultivars are being produced constantly.  They are mainly of Chinese and Japanese origin.  Most species are known as clematis in English, while some are also known as traveller's joy, a name invented for the sole British native, "C. vitalba", by the herbalist John Gerard; virgin's bower for "C. viticella"; old man's beard, applied to several with prominent seedheads; leather flower for those with fleshy petals; or vase vine for the North American "Clematis viorna".
Answer: Clematis