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Merremia cliffordii

Interesting Facts

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Description

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Family Convolvulaceae

Herbs or shrubs , usually with twining or climbing stems or erect , often with milky juice. Leaves alternate, simple , entire, dissected , or compound , absent in parasitic species. Flowers solitary, axillary or in cymes, racemes , panicles, umbels, or capitula, bisexual , actinomorphic , usually 5-merous, often showy. Sepals free , often persistent , sometimes enlarged in fruit. Corolla sympetalous , funnelform , campanulate , salverform , or urceolate ; limb subentire or deeply lobed . Stamens alternating with corolla lobes , adnate to corolla; filaments filiform , equal or unequal in length ; anthers introrse , laterally and longitudinally dehiscing; pollen smooth or finely spiny . Disc ringlike or cupular. Ovary superior, mostly 2-carpellate, 1- or 2-loculed, rarely 3- or 4-loculed; ovules basal, erect. Styles 1 or 2, terminal (gynobasic in Dichondra) or very short or absent; stigma entire or 2- (or 3) -lobed, rarely peltate. Fruit a capsule, dehiscing by valves , circumscissile, or irregularly shattering, less often a berry or nutlike. Seeds usually trigonous , smooth or pubescent .

About 58 genera and 1650 species: widely distributed in tropical , subtropical , and temperate regions ; 20 genera and 129 species in China.

Aniseia biflora (Linnaeus) Choisy and A. stenantha (Dunn) Ling, recognized in the Fl. Reipubl. Popularis Sin., are here treated as Ipomoea biflora and I. fimbriosepala, respectively, because both have pantoporate and spinulose pollen. Strictly speaking, Aniseia is a neotropical genus of about five species, of which A. martinicensis (Jacquin) Choisy is widely naturalized as a common weed in rice paddies in Thailand and other southeast Asian countries. It will probably be found in S China eventually.

The family is important in China for food plants (Ipomoea batatas (Linnaeus) Lamarck and I. aquatica Forsskål), several ornamentals (Ipomoea), several medicinal plants (Erycibe, Ipomoea, Cuscuta, Merremia, Dichondra, Evolvulus), and numerous noxious weeds (Cuscuta, Calystegia, Convolvulus) .

Pollen aperture type and surface ornamentation are important characters in the classification of Convolvulaceae at the generic level and above. The most critical feature of the pollen is whether the grain surface is spiny or not. This distinction separates the eight tribes recognized by Austin (Ann. Missouri Bot. Gard. 60: 306-412. 1973) into two rather cohesive groups. A low magnification (20 ) is adequate for discerning the presence or absence of minute spines on the surface.

For the successful identification of Convolvulaceae, both flowering and fruiting material should be collected. The first key to genera requires adequate fertile material with both flowers and fruit, and requires use of a pollen character. The second key may be used as an aid to identification where material is lacking flowers or fruit, but in some instances it is still partially dependent upon having both flowers and fruit.[1]

Genus Merremia

Herbs or shrubs , often twining , sometimes prostrate . Leaves usually petiolate , rarely sessile, margin entire, dentate , or palmately or pedately lobed or compound . Flowers axillary , solitary or in few- to many-flowered, variously branched cymose inflorescences; bracts usually small. Sepals variable in shape , often convex , subequal or outer 2 smaller, persistent , often enlarged in fruit. Corolla often yellow or white, sometimes with a darker center, funnelform or campanulate , usually glabrous , or midpetaline bands ± sericeous , sometimes only at apex; limb entire or ± 5-angled. Stamens included , often unequal; anthers often spirally twisted; filaments dilated basally, filiform distally; pollen 3-12-colpate or polyrugate, not spiny . Disc ringlike. Pistil included; ovary (imperfectly 2-) 4-loculed, 4-ovuled. Style 1, filiform; stigmas 2-globular. Capsule 1-4-loculed, usually 4-valved or ± irregularly dehiscing. Seeds 4 or fewer, glabrous or pubescent to villous especially at margin.

Approximately 80 species: tropical regions of Africa, Asia, Australia, North and South America; 19 species in China.

The generic name Merremia was published as a nomen nudum by Dennstedt (Schlüssel Hortus Malab. 12, 23, 34. 1818). Several modern floras attribute the valid publication of the name to H. Hallier (Bot. Jahrb. Syst. 16: 581. 1893), but Endlicher (1841) actually validated the name.

Merremia is often confused with Ipomoea, which has pantoporate , spiny pollen, straight anthers and very few species with yellow corollas. It is also confused with Operculina, which consistently has a fruit with a circumscissile lid that detaches first, leaving a fragile endocarp that shatters irregularly. The distribution of hairs on the corolla is taxonomically important in Merremia; this is most easily discerned on mature flower buds.[2]

Taxonomy

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Similar Species

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Members of the genus Merremia

ZipcodeZoo has pages for 13 species, subspecies, varieties, forms, and cultivars in this genus:

M. aegyptia (Hairy Merremia) · M. aurea (Yellow Morning Glory) · M. bipinnatipartita (Merremia) · M. cissoides (Roadside Woodrose) · M. discoidesperma (Crucifixion Bean) · M. dissecta (Alamo Vine) · M. gangetica (Kidney Leaf Morning Glory) · M. hederacea (Ivy Woodrose) · M. peltata (Merremia) · M. quinquefolia (Batatilla Blanca) · M. sibirica (Merremia) · M. tuberosa (Hawaiian Woodrose) · M. umbellata (Aguinaldo Amarillo)

More Info

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Further Reading

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Notes

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Contributors

Identifiers

Footnotes

  1. Ruizheng Fang & George Staples "Convolvulaceae". in Flora of China Vol. 16 Page 271. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. "Merremia". in Flora of China Vol. 16 Page 291. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
Last Revised: 2012-07-25