Systematics and nomenclature
The Ginger family, or Zingiberaceae, belongs to the order
Zingiberales (previously called Scitamineae). It is a very natural order, which
today is divided into eight families falling into two groups, the Banana group
and the Ginger group, the latter being the more advanced.
Key to the families
1. Stamens 5 or 6 (Banana group)..................................................................................2
Stamen 1 (Ginger
group)...............................................................................................5
2. Flowers unisexual, plant monoecious,
with latex....................................Musaceae
Flowers bisexual, without
latex.............................. 3
3. Stem woody, 2 lateral petals joined,
enclosing the anthers...........Strelitziaceae*
Stem not woody, 2 lateral petals not
joined...............................................................4
4. Median petal free, forming a
labellum; leaves finely reticulately veined
....................................................................................................................Lowiaceae
Median petal not forming a
labellum...............................................Heliconiaceae*
5. Flowers symmetrical along the median
axis (zygomorphic), sepals joined at base
........................................................................................................................................6
Flowers asymmetrical, sepals
free.............................................................................7
6. Leaves distichous, sheaths
open.........................................................Zingiberaceae
Leaves spirally arranged, sheaths
closed..................................................Costaceae
7. Leaves with a pulvinus below the leaf
blade.......................................Marantaceae
Leaves without
pulvinus...........................................................................Cannaceae*
The
families with an asterisk are not native to Thailand, but they are all
represented as ornamentals: Strelitzia reginae, the Bird-of-Paradise
flower, Ravenala madagascariensis, the Travellers Tree, Heliconia
rostrata and other Heliconia species, as wdl I as Canna hybrids
are very popular and sometimes naturalized around villages.
The relationship among the families have
been studied from many points of view. Besides the traditional morphological
analysis and description, anatomy, chemistry, cytology, palynology and most
recently through molecular analysis combined with a cladistic treatment of the
data. Even the most refined methods of today have not been able to change much
in the division into eight families.
In this book the Ginger family, the
Zingiberaceae, is in focus. This was by Schumann (1904) divided into four
tribes, all of which occurs in Thailand. A tribe is a group of genera that have
a number of characters in common and thus deviates from the other tribes. Still
a tribe is not so clearly defined, that it deserves a higher rank of family.
The Schumann system was used in the “Gingers of Peninsular Malaysia and
Singapore” by Larsen & al. (1999).
A very recent phylogenetic analysis,
based on molecular studies by Kress & al. (2002), suggests several changes
to this current system. It is here proposed to divide the family into 4
subfamilies of which only the two first are native to Thailand.
1. Zingiberoideae
Tribe Zingibereae
Globbeae
2. Alpinioideae
Tribe Alpinieae
Riedelieae
3. Tamijioideae, only one species, Tamijia
flagellaris in N. Borneo
4.
Siphnochiloideae, one genus, Siphonochilus, withe. 15 species in Africa
Key to the tribes native to Thailand
1. Lateral staminodes well developed,
free from the labellum, the plane of distichy
of the leaves parallel to the
rhizome.......................................................................2
Lateral staminodes reduced to small
teeth at base of labellum or wanting........3
2. Ovary unilocular with parietal
placentation..............................................Globbeae
Ovary 3-locular (very rarely unilocular)
with central placentation. Zingibereae
3. Fruit a long, thin
capsule.........................................................................Riedelieae
Fruit various, usually more or less
spherical, never a long, thin capsule ... Alpinieae
Characters used for distinguishing the
tribes are mainly floral. One diagnostic vegatative character, however, was
discovered rather late: The importance of the plane of distichy of the leaves.
In all Zingiberaceae the leaves are arranged in two rows, distichous, whereas
in the Costaceae they are spirally arranged. In the three of the four tribes
the plane of distichy is parallel to the rhizome while in one, the Alpinieae,
it is transverse to the rhizome. It is usually easy to see if the plant is dug
from the ground and the rhizome is of a certain length, but in some small
species with poorly developed underground stem it may be less obvious. Among
the floral characters the development of the lateral staminodes is highly
rated. In the Globbeae and most Hedychieae they are large and free, while in
the Zingiber they form part of the labellum (lip); in the Alpinieae they are
strongly reduced. The anther crest is a most diverse structure. It is an
outgrowth from the connective, the sterile tissue between the pollen sacs. The
ovary in the Monocotyledones are formed of 3 carpels and therefore basically
3-locular with the ovules placed centrally in the axils between the carpels.
This is called central or axile placentation. In the Globbeae the carpels are
joined only along the margins and the placentation therefore becomes parietal,
i. e. the ovules are placed on the wall along the sutures. In very few species
in the Zingibereae the division of the ovary is dissolved during the
development of the capsule, in this case the placenta becomes central in an
unilocular capsule as in some species of Boesenbergia.
The
determination of a Ginger plant begins with a careful analysis of the flower.
This is very del icate in most species and short-lived. Therefore observation
of the structures should be done when the flower is fresh or, if this is not
possible, then it should be preserved in 70% alcohol. For further instructions
in collecting and preserving Gingers see chapter 11.
In chapter 6 the genera found in
Thailand are enumerated. It has been necessary here to use a number of
taxonomic and nomenclatorial terms that may need a further explanation. Please
check any unknown term in the glossary (page 169).
The names of the genera in this book are
followed by the name of the author and the year of publication. This is often
regarded as an unnecessary burden in literature that is not strictly for
scientific use. It is, however, a very infonnative addition that we have chosen
to bring. It gives the reader instant infonnation about who described the genus
and when. In an appendix all known species in Thailand are enumerated with full
literature reference.
Many species’ names change over time.
This may be quite confusing, but it is inevitable as we gain more knowledge on
the Gingers. Therefore synonyms occur. Synonyms are different names given to
the same species. If more names are available for a species, the oldest name is
the valid one according to the International Code of Botanical Nomenclature.
Still no name can be older than 1753, referring to Linnaeus’ work: Species
Plantarum published that year and regarded the starting point of botanical
nomenclature. Only valid names are used throughout and very rarely we have
added here what the taxonomists call full synonymy, meaning listing all names used
for a species since the starting point of nomenclature in 1753. Only in cases
where a synonym has been in common use in literature referring to Thai plants,
we have added them in parenthesis.
0 Comment:
Post a Comment