Encyclopedia : Taxonomy

Family Convolvulaceae

Copyright 1998-2022 Yoshiaki Yoneda

Asagao, the Japanese name for the morning glory, belongs to Convolvulaceae (the morning glory family) in the plant classification. Convolvulaceae, composed of about 50 genera and 1500 species, is distributed across the world's tropical and subtropical regions. Only a small number of species are found in temperate areas. Most species of Convolvulaceae are herbs. The stems of these herbs are twining or prostrate. The flowers are large and funnel-shaped, bell-shaped or crateriform. Many species each have a distinct flower color. Shrubby species are rare and only a few become trees.

The flower has one pistil composed of 2 carpels. The ovary has 2 or 4 locules. (In section Pharbitis of genus Ipomoea, the pistil is composed of 3 carpels and 3 locular ovaries). The flower has 5 stamens. Pollen grains are spheroidal and prolate. Pollen tubues develop from germination colpae or pores.). Most species in many genera, including Convolvulus, have 3 colpae (some species have 4 or 5 colpae-pollen). Calystegia species have ca. 30 pores, while Ipomoea species have 100-200. In the tribes Ipomoeeae and Argyreieae, many spiny protuberances are observed on the outer wall (exine) of the pollen grain. This type of pollen is called the echinate type. In other tribes, such spiny protuberances are not found, so the pollens are called the smooth-surface or psilate type. The fruits are ordinarily dehiscent capsules, while some species have baccate fruits or nut-like fruits.

Convolvulaceae have been studied taxonomically by H. G. Hallier (1893), A. Peter O. R. (1937), S. J. van Ooststroom (1938~43), H. Melchior (1964) and D.F. Austin (1973,1975). The tribe Cuscuteae has special characteristics, including a parasitic life and spiral embryos without cotyledons. It Is therefore sometimes classified as an independent family, Cuscutaceae, separate from Convolvulaceae. Hallier focused on the surface morphology of pollen grains and classified the family Convolvulaceae into two subfamilies: a smooth-surface subfamily, or psiloconiae and a spiny-surface subfamily, or echinoconiae. He considered that the latter would derive from the former phylogenetically. Concerning the number of chromosomes, the tribe Convolvuleae, including the genera Convolvulus and Calystegia, have basic numbers x=10,11,12, while other tribes have x=14,15. Convolvulaceae has been classified according to various criteria, including the morphology of pollen and pistils, the dehiscence of capsules and the chromosome number.

The author introduces here the classification of D. F. Austin (1973).


Surface type of pollen grainStyleFruitChromosome number
1-1Ericibeaesmooth surface colpate pollenstyle entire, bifid or absentbaccate and nut-like fruit2n=30
1-2Cresseaesmooth surface colpate pollenone bifid style or two free stylescapsule dehiscent2n=28
1-3Convolvuleae smooth surface colpate pollenstyle entirecapsule dehiscent2n=20,22,24,30,
40,44,50 etc.
1-4Merremioidssmooth surface colpate pollenstyle entirecapsule irregularly dehiscent2n=28,30
1-5Ipomoeaeprickly surface porate pollenstyle entirecapsule regularly dehiscent2n=28,30,60,90
1-6Argyreieaeprickly surface porate pollenstyle entiresap fruit2n=28,30
1-7Poraneaesmooth 3-colpate pollenentire, or less commonly bifid stylecapsule indehiscent2n=26
1-8Dichondreaesmooth surface colpate pollentwo styles and two fruit capsulescapsule dehiscent2n=30
1-9Cuscuteaesmooth surface colpate pollentwo or one stylecapsule indehiscent or transversely divided2n=14,28,30

Sanshikihirugao
Dwarf convolvulus
Convolvulus tricolor
Seiyoohirugao
Field bindweed
Convolvulus arvensis
Seiyoohirugao
Field bindweed
Convolvulus arvensis
Seiyoohirugao
Field bindweed
Convolvulus arvensis
Hirugao
Japanese bindweed
Calystegia japonica
Kohirugao
Japanese bindweed
Calystegia hederacea
Hamahirugao
Sea bindweed
Calystegia soldanella
Husenasagao
Operculina turpethum
Flower
Husenasagao
Operculina turpethum
Capsule
Husenasagao
Operculina turpethum
Dihisced capsule
Baraasagao Wood rose
Merremia tuberosa
Baraasagao Wood rose
Merremia tuberosa
Tutanohahirugao
Merremia hederacea
Flower
Tutanohahirugao
Merremia hederacea
Flower
Kirehahirugao
Merremia dissecta

Flower
Kirehahirugao
Merremia dissecta
Leaf
Kirehahirugao
Merremia dissecta
Capsule
Kirehahirugao
Merremia dissecta
Matured capsule
Hosobaasagao
Merremia tridentata
ssp. hastata

Oobaasagao
Argyreia nervosa
Oobaasagao
Argyreia nervosa
Flower
Oobaasagao
Argyreia nervosa
Leaf
Oobahamaasagao
Stictocladia tilifolia

Oobahamaasagao
Stictocladia tilifolia
Oobahamaasagao
Stictocladia tilifolia
Aoigoke
Dichondra repens
Leaf
Aoigoke
Dichondra repens

Hamanenasikazura
Cuscuta chinensis
Hamanenasikazura
Cuscuta chinensis
Flower
References
  1. Clarke, C. B. (1883) Convolvulaceae. In The Flora of British India IV:179 ed. Hooker, J.D.
  2. Hallier, H. (1893) Versuch einer nat rlichen Gliederung der Convolvulaceen auf morphologischer und anatomischer Grundlage. Bot. Jahrb. Sys. 16: 453-591.
  3. Peter, A. (1897) Convolvulaceae. In: Natürlichen Pflanzenfamilien IVa:25~31 ed.by A. Engler & Prantl, K.
  4. Wilson, K. A. (1960) The Genera of Convolvulaceae in the Southeastern United States J. Arnold Arboretum 41:298-317.
  5. Valentine, D. H. (1972) Convolvulaceae; In Flora Europaea (ed. Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M., Webb, D. A.) Cambridge, Univ. Press.
  6. Austin, D. F. (1973) The American Erycibeae (Convolvulaceae): Maripa, Dicranostyles, and Lysiostyles I. Systematics. Ann. Missouri Bot. Gard. 60: 306-412.
  7. Austin, D. F. (1975) Family 164.Convolvulceae in Flora of Panama (Woodson, R. E., Jr. & Schery, R.W. & Collabortors) Ann. Missouri Bot. Gard. 62: 157-224.
  8. Powell, D. A. (1979) The Convolvulaceae of the Lesser Antilles J. Arnord Arbor. 60: 219.
  9. Yoneda, Y. (1989) Convolvulaceae In: Grand dictionary of horticultural plants vol. 4: 149 (edited by Youtarou Tukamoto). Shougakkan.


Edited by Yuuji Tsukii (Lab. Biology, Science Research Center, Hosei University)