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7. Lauraceae

樟科 zhang ke

Authors: Shugang Li, Xi-wen Li, Jie Li, Puhua Huang, Fa-Nan Wei, Hongbin Cui & Henk van der Werff

Trees or shrubs (Cassytha a twining parasitic perennial herb with leaves reduced or absent), mostly evergreen (deciduous in temperate regions), sometimes dioecious. Bark and foliage usually aromatic. Leaves usually alternate, occasionally opposite or subopposite or verticillate, simple, usually entire, rarely lobed (Sassafras), mostly pinninerved and subpalmately veined, or often triplinerved, usually punctate and leathery, estipulate. Flowers in usually axillary, occasionally subterminal, panicles, spikes, racemes, or pseudoumbels, generally bisexual, sometimes unisexual, actinomorphic, mostly 3-merous, also 2-merous, small, greenish, yellowish, or white. Perianth biseriate, of usually 4 or 6 basally connate usually undifferentiated sepal-like segments, deciduous or persistent; perianth tube usually persisting as a cupule at base of fruit. Androecium typically of 4 whorls of 3 stamens each, adnate to perianth tube, innermost whorl rarely united, usually reduced to staminodes; filaments usually free, 3rd whorl usually bearing 2 usually sessile and distinct basal glandular protuberances; anthers basifixed, 2-celled or 4-celled at anthesis, those of 2 outer whorls mostly introrse, inner 3rd whorl extrorse, dehiscing by flaplike valves opening upward. Pistil 1; ovary usually superior, 1-loculed; ovule solitary, anatropous, pendulous, placentation parietal; style 1; stigma 1, occasionally 2- or 3-lobed. Fruit a drupe or berry usually surrounded at base by enlarged and often persistent perianth tube seated on a large receptacle or pedicel. Seed with large straight embryo; endosperm absent.

About 45 genera and 2000-2500 species: tropical and subtropical regions but mostly in tropical SE Asia and tropical America; 25 genera (two endemic, two introduced) and 445 species (316 endemic, three introduced) in China; two additional species (one endemic) are of uncertain placement.

The Lauraceae are economically important as sources of medicine, timber, nutritious fruits (e.g., Persea americana), spices (e.g., Cinnamomum cassia, C. subavenium, Laurus nobilis), and perfumes. The fruits of Actinodaphne, Cinnamomum, Cryptocarya, Lindera, Litsea, and Syndiclis contain abundant oil and fat. Cinnamomum trees, such as Cinnamomum camphora, C. glanduliferum, and C. parthenoxylon, yield camphor and essential oil, which are used for making perfumes and medicines. The bark of C. cassia and the roots of Lindera aggregata are famous traditional Chinese medicines.

The Chinese species of Lauraceae remain poorly known and difficult to identify. The main reason for this is that for a substantial number of species the fruits or flowers are not known. This makes generic placement of such species uncertain, since most genera are defined by floral characters. A second problem is that characters of both flowers and fruits are used in most generic keys and since specimens almost never bear both flowers and fruits, identification is often almost impossible. A drastic remedy for this problem would be to make keys based on flowering specimens and list species known only with fruits as incompletely known species and not include them in the keys. This approach has not been followed in this treatment.

The genera are here maintained as they have been recognized in earlier works on Chinese Lauraceae. The present authors are aware that this will seem inconsistent; for instance, in the case of Sassafras, species with 2-celled and 4-celled anthers are included in the same genus, while in other cases pairs of genera are separated based on this character (for example Lindera-Litsea, Alseodaphne-Nothaphoebe, and Parasassafras-Sinosassafras). Generic boundaries in the Litsea group (Actinodaphne, Dodecadenia, Iteadaphne, Lindera, Litsea, Neolitsea, Parasassafras, and Sinosassafras) are not well defined, and generic concepts are likely to change after further research.

Aside from these problems, there are a number of vegetative characters that are helpful in the identification process. They are listed below.

Leaves opposite or subopposite: Beilschmiedia p.p., Caryodaphnopsis, Cinnamomum p.p.

Leaves verticillate or clustered: Actinodaphne, Neolitsea; rarely in Lindera (L. megaphylla) and Litsea (L. verticillata); weakly clustered in Alseodaphne, Dehaasia, Machilus, Phoebe.

Leaves triplinerved and alternate: Cinnamomum p.p., Cryptocarya p.p., Lindera p.p., Neocinnamomum.

Leaves triplinerved and clustered: Neolitsea.

Leaves triplinerved and opposite: Caryodaphnopsis, Cinnamomum p.p.

Leaves lobed: Lindera p.p., Sassafras.

Leaves with tufts of hairs in axils of lateral veins: Cinnamomum p.p.

The three genera Machilus, Persea, and Phoebe cannot be identified adequately by floral characters; they have been separated traditionally on the fruit characters listed in the key.

Li Hsi-wen et al. 1982. Lauraceae. In: Li Hsi-wen, ed., Fl. Reipubl. Popularis Sin. 31: 1-463.

One of the present authors (van der Werff) provides this alternative key to genera. Nothaphoebe is deliberately not included; see the comment under that genus (p. 200).


Alternative key to genera

1 Twining parasitic vines with minute scalelike leaves.   25 Cassytha
+ Leafy trees or shrubs   (2)
       
2 (1) Plants deciduous, flowering when leafless or with unfolding young leaves   (3)
+ Plants evergreen, flowering when mature leaves are present   (5)
       
3 (2) Inflorescences racemose.   7 Sassafras
+ Inflorescences umbellate   (4)
       
4 (3) Stamens with 4 locelli or staminodia with 4 rudimentary locelli.   3 Litsea
+ Stamens with 2 locelli or staminodia with 2 rudimentary locelli.   5 Lindera
       
5 (2) Flowers unisexual   (6)
+ Flowers bisexual   (15)
       
6 (5) Flowers 2-merous, with 4 tepals   (7)
+ Flowers 3-merous, with 6 tepals   (8)
       
7 (6) Anthers 2-celled; leaves evenly distributed along twigs; plants cultivated.   1 Laurus
+ Anthers 4-celled; leaves clustered; plants native.   2 Neolitsea
       
8 (6) Inflorescences umbellate, involucral bracts present at base of young umbels   (9)
+ Inflorescences paniculate, racemose, 1-flowered or umbellate, if umbellate, involucral bracts lacking   (11)
       
9 (8) Anthers 2-celled.   5 Lindera
+ Anthers 4-celled   (10)
       
10 (9) Leaves verticillate and umbels sessile along leafless internodes.   8 Actinodaphne
+ Leaves alternate or rarely whorled, if whorled, umbels pedicellate and predominantly in axils of leaves.   3 Litsea
       
11 (8) Inflorescences paniculate.   8 Actinodaphne
+ Inflorescences racemose, umbellate, or 1-flowered   (12)
       
12 (11) Inflorescences umbellate   (13)
+ Inflorescences 1-flowered, sometimes several 1-flowered inflorescences along a leafless short shoot and thus appearing racemose   (14)
       
13 (12) Anthers 2-celled.   19 Sinosassafras
+ Anthers 4-celled.   9 Parasassafras
       
14 (12) Anthers 2-celled.   6 Iteadaphne
+ Anthers 4-celled.   4 Dodecadenia
       
15 (5) Leaves opposite and tepals strongly unequal, outer 3 much smaller than inner 3.   16 Caryodaphnopsis
+ Leaves alternate, if leaves subopposite, tepals equal   (16)
       
16 (15) Flowers 2-merous, tepals 4.   23 Syndiclis
+ Flowers 3-merous, tepals 6   (17)
       
17 (16) Anthers 2-celled   (18)
+ Anthers 4-celled   (22)
       
18 (17) Stamens 3.   20 Endiandra
+ Stamens 9   (19)
       
19 (18) Leaves clustered; bark of twigs pale gray, contrasting with dark petioles.   15 Dehaasia
+ Leaves evenly distributed or subopposite; bark of twigs and petioles concolorous   (20)
       
20 (19) Base of tepals united in a short tube; free parts of tepals falling off in old flowers, leaving pistil enclosed in floral tube.   24 Cryptocarya
+ Tepals free or nearly so, falling off in old flowers and leaving pistil fully exposed on pedicel   (21)
       
21 (20) Stamens 6 or 9, included in flowers, shorter than tepals; anther cells lateral.   21 Beilschmiedia
+ Stamens 6, as long as or longer than tepals; anther cells apical.   22 Sinopora
       
22 (17) Leaves strongly triplinerved, alternate; flowers in fascicles arranged along a branched inflorescence or sessile in leaf axils; tepals to 2 mm.   11 Neocinnamomum
+ Leaves pinnately veined or infrequently triplinerved; flowers in panicles, not in fascicles; tepals mostly more than 2 mm   (23)
       
23 (22) Leaves alternate, pinnately veined, clustered along twigs, without domatia; terminal buds not protected by whorls of bracts, rings of bract scars lacking at base of seasonal growth.   18 Alseodaphne
+ Leaves alternate or opposite, pinnately veined or triplinerved, domatia sometimes present, if somewhat clustered then terminal buds protected by whorls of bracts and rings of bract scars present at base of seasonal growth   (24)
       
24 (23) Leaves triplinerved or pinnately veined, if pinnately veined then domatia present.   10 Cinnamomum
+ Leaves pinnately veined and domatia lacking   (25)
       
25 (24) Tepals clasping fruits.   12 Phoebe
+ Tepals spreading to reflexed or deciduous   (26)
       
26 (25) Tepals spreading to reflexed in fruit.   14 Machilus
+ Tepals deciduous in fruit   (27)
       
27 (26) Fruit large (5-15 cm), pear-shaped; plants cultivated for their fruit.   17 Persea
+ Fruit small (ca. 1 cm in diam.), ± round; plants native.   14 Machilus

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