CLASSIFICATION OF MAGNOLIACEAE
By Richard B. Figlar June 2004
Except for the very distinct genus Liriodendron, taxonomists have long debated the classification of the other lineages comprising Magnoliaceae, known as subfamily Magnolioideae. However, with the advance of molecular systematics (DNA sequencing) beginning in the early 1990’s (Qiu et al, 1995a,1995b Azuma et al. 1999, 2001; Kim et al. 2001, and others), coupled with a comprehensive re-examination of morphological characters (Figlar, 2000, 2002a, 2002b; Sima et al., 2001, Baranova & Jeffrey, 2000; Nooteboom, 1985, 1998, 2000; Li and Conran 2003; Figlar & Nooteboom, 2004), it is clear that Magnolioideae is considered to contain just one genus, Magnolia.
Up until the latter part of the last century, there had been widespread support for the 11 genera treatment for Magnolioideae, devised by the famous Magnoliaceae taxonomist, James E. Dandy of the British Museum of Natural History. In 1927 he codified his system of Magnolioideae as consisting of Magnolia, Manglietia, Michelia, and Talauma, along with several minor genera; Aromadendron, Kmeria, Pachylarnax, Alcimandra, and Elmerrillia (later he recognized Paramichelia and Tsoongiodendron as well). Dandy based this classification on his own morphological observations and the observations of some of the taxonomists that preceded him: more than 2 seeds or ovules (usually 4) per fruiting carpel representing Manglietia; axillary flower position and stipitate gynoecium for Michelia; and on woody fruits whose carpels fall apart rather than split to release seeds in Talauma, whereas he defined Magnolia by its 1 or 2 seeds (ovules) per carpel, terminal flowers & sessile gynoecium, and carpels that split longitudinally to release seeds. He justified the minor genera based mostly on different combinations of characters that he had defined for the 4 major genera, i.e. Elmerrillia is like Michelia except for its sessile gynoecium, and Paramichelia is similar to Michelia except for it’s woody Talauma-like fruits, etc. He also maintained separation of the two (now three) species with unisexual flowers as genus Kmeria. Later, noted Chinese Magnoliaceae botanist, Law Yu-Wu (Liu Yu-Hu), made minor modifications (added four additional genera) to Dandy’s system in 1984 and in subsequent years. Dandy’s system (modified by Liu) is still followed in the new book, Magnolias of China (Liu et al., 2004).
Looking back, it is easy to see how Dandy misconstrued the ranks and constituent species of many of the Magnolioideae lineages. After all, he had built his system before all the lineages had been discovered! Evidently, he also put strong taxonomic weight on three - taxonomically weak – characters: so called axillary flowers, slight differences in fruit dehiscence, and the stipitate gynoecium. Moreover, he had apparently never observed important “living” characters that cannot readily be seen in herbarium specimens (such as precocious flowering, persistent/caduceus stamens, proleptic/sylleptic branching, and open/conduplicate leaf vernation), and of course he didn’t have access to DNA sequencing. Otherwise, Dandy did quite well considering the tools he had to work with.
James E. Dandy died in 1976 and Liu Yu-Hu in 2004. In honoring them, I’d like to think that this new classification finishes their work.
Classification for Magnolioideae (follows Figlar and Nooteboom, 2004)
Genus Magnolia
Subgenus Magnolia
Branches normally produced by syllepsis (except in subsect. Oyama)
Leaf vernation (prefoliation) conduplicate
Flowers terminal.
Introrse anther dehiscence
Gynoecium sessile
Fruit more/less ovoid or ellipsoid with fused carpels until dehiscence
Mid-late season flowering in non-tropical spp. (Generally, one cannot discern the presence of flower buds until the season in which the flowers are produced.)
Pollen large, diameter usually > 50 µm.
Stamens caducous during male phase (except in subsect. Oyama).
Section Magnolia
Leaves evergreen or sometimes facultatively deciduous in one sp., M. virginiana.
Stipules adnate to most of the petiole in one sp., M. virginiana, or adnate to the base of the petiole, thus appearing to be free in all other spp. of this section.
Usually two ovules per carpel.
Stomata group number 5 (see Baranova & Jeffrey, 2000).
Section Gwillimia
Leaves evergreen.
Stipules adnate to the petiole.
Usually 2 ovules per carpel.
Stomata group number 9.
Subsection Gwillimia
Stipules adnate to (mostly) the entire length of the petiole.
Carpels longitudinally dehiscent.
Stylar beaks, in fruit, often flattened.
Subsection Blumiana
Stipules adnate to 50% to 100% the length of the petiole.
Carpels dehiscing mostly circumscissile.
Section Talauma
Leaves evergreen.
Long connective appendage (embedded in the gynoecium) except in subsect. Talauma.
Carpels dehiscing circumscissile except in subsect. Cubenses.
Stomata group numbers 5,3, and 2.
Subsection Talauma
Stipules adnate to the petiole.
Carpels dehiscing circumscissile
Stomata group number 5.
Subsection Dugandiodendron
Stipules free (or appearing so) from the petiole.
Long connective appendage embedded in gynoecium (except in M. calophyllum, M. magnifolium
and M. calimaense).
Carpels dehiscing circumscissile.
Stomata group numbers 2 and 3.
Subsection Cubenses
Stipules free (or appearing so) from the petiole.
Long connective appendage embedded in gynoecium
Carpels longitudinally dehiscent.
Stomata group number 2.
Section Manglietia
Leaves evergreen (except in one sp., M. decidua)
Early season leaves sometimes arranged in false whorls (flushing).
Usually 4 or more ovules per carpel.
Stomata group number 8.
Section Kmeria
Leaves evergreen.
Stipules attached to > 50% of the petiole.
Flowers unisexual.
Usually 2 ovules per carpel.
Stomata group number 11.
Section Rytidospermum
Leaves deciduous
Branches produced by syllepsis or prolepsis.
Usually 2 ovules per carpel.
Stomata group number 7.
Subsection Rytidospermum
Branches produced mostly by syllepsis.
Early-season leaves arranged in false whorls (flushing).
Stamens caduceus during male phase.
Subsection Oyama
Branches produced mostly by prolepsis.
Leaves arranged “normally’ (no flushing).
Stamens mostly persistent during male phase.
Section Auriculata
Leaves deciduous witrh auriculate bases (glabrous).
Early season leaves arranged in false whorls (flushing).
Flowers semi-precocious.
Tepals without purple spot on base of adaxial surface.
Stomata group number 6.
Section Macrophylla
Leaves deciduous with cordate to auriculate bases (glaucous to m/l pubescent).
Early season leaves only moderately flushed.
Tepals with purple spot on base of adaxial surface.
Stomata group number 4.
Subgenus Yulania
Branches normally produced by prolepsis (less pronounced in tropical spp.)
Leaf vernation (prefoliation) conduplicate
Flowers terminal and/or on proleptic brachyblasts.
Introrse or latrorse anther dehiscence.
Gynoecium sessile or stipitate.
Fruit more/less cylindrical in shape, often apocarpus, longitudinally dehiscent, or occasionally with lignified carpels resulting in a more ellipsoidal shape which is dehiscent circumscissile.
Precocious flowering, generally before new leaves appear (Usually, one can discern the presence of flower buds during the summer preceding the year the flowers are produced.)
Pollen small, diameter usually < 50 µm.
Stamens persistent during male phase.
Section Yulania
Leaves deciduous.
Flowers terminal or sometimes on proleptic brachyblasts.
Latrorse anther dehiscence.
Fruits cylindrical (not apocarpus).
Usually 2 ovules per carpel.
Stomata group number 13.
Subsection Yulania
Tepals white, pink, or purple (sometimes outer whorl sepaloid)
Fruits cylindrical.
Pronounced precocious flowering.
Subsection Tulipastrum
Tepals green to yellow (outer whorl sepaloid).
Precocious flowering less pronounced.
Section Michelia
Leaves evergreen.
Usually 2 to 6 (to many) ovules per carpel.
Subsection Michelia
Flowers mostly on proleptic brachyblasts, rarely terminal on long shoots.
Gynoecium stipitate.
Latrorse anther dehiscence.
Fruits cylindrical / apocarpus or occasionally ellipsoidal syncarpus.
Usually 2 to 6 (to many) ovules per carpel.
Stomata group number 12.
Subsection Elmerrillia
Flowers mostly on proleptic brachyblasts, rarely terminal on long shoots
Gynoecium sessile.
Introrse anther dehiscence.
Fruits cylindrical but not apocarpus, or occasionally ellipsoidal syncarpus/circumscissile.
Usually 2 to 6 ovules per carpel.
Stomata group number 12.
Subsection Maingola
Flowers terminal (on long shoots) or rarely on proleptic brachyblasts.
Gynoecium variably stipitate.
Introrse anther dehiscence.
Fruits cylindrical (not apocarpus).
Usually 2 ovules per carpel.
Stomata group numbers 12 & 14.
Subsection Aromadendron
Flowers terminal (on long shoots) or rarely on proleptic brachyblasts.
Gynoecium stipate except in M. ashtonii.
Introrse anther dehiscence.
Fruits with thick connate mesocarp, superficially ovoid/ellipsoid, dehiscent circumscissile.
Stomata group number 14.
Subgenus Gynopodium
Leaves evergreen.
Branches normally produced by syllepsis.
Leaf vernation (prefoliation) open, not conduplicate.
Plants entirely glabrous.
Flowers bisexual or tree androdioecious.
Fruit more/less ovoid or ellipsoid with fused carpels until dehiscence.
Carpels dehiscing longitudinally.
Mostly 2 to sometimes 8 ovules per carpel.
Gynoecium shortly stipitate (sessile in M. praecalva & M. pleiocarpa)
Section Gynopodium
Tree androdioecious (or probably bisexual in M. nitida var. nitida & M. kachirachirai)
Gynoecium shortly stipitate.
Carpels dehiscing mostly along dorsal suture.
Ovules 2 per carpel (up to 4 in M. kachirachirai)
Stomata group number 11.
Section Manglietiastrum
Flowers bisexual.
Gynoecium sessile (but shortly stipitate in M. sinica)
Carpels dehiscent mostly along the ventral suture especially at apex of fruit.
Usually 3 to 8 ovules per carpel.
Stomata group number 10.
References:
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