**2.** *Phalaenopsis* **and related genera**

#### **2.1 Classification**

The genus *Phalaenopsis* (Orchidaceae) is classified as subfamily *Epidendroideae*, tribe *Vendeae*, and subtribe *Aeridinae* [1]. The native species of *Phalaenopsis* are distributed throughout northern Australia to southern India, China, and Taiwan in tropical Asia. Cultivars called moth orchids (*Phalaenopsis* and *Doritaenopsis*) are mainly generated by crossing native species of genus *Phalaenopsis* and genus *Doritis* (*Doritis pulcherrima*). Because *Phalaenopsis* is amenable to artificial crossing with other species and even other genera, such as *Doritis*, *Ascocentrum,* and *Vanda*, many of the cultivars have been produced as interspecific and intergeneric hybrids [2].

#### *2.1.1 Morphological classification*

*Phalaenopsis* Orchids have been classified morphologically by unique features, such as pollen. *Phalaenopsis* are epiphytic orchids, which live sticking to trees. They are monopodial plants with a short stalk and three to six widely and fleshy leaves. Their flowers consist of sepal, petal, lip, and column, which are flower structures particular in Orchids. The genus *Phalaenopsis* are defined by Blume in 1825 and has been classified by many taxonomists mainly based on morphological features of flower structure [3] and the number of pollens [2, 4] and based on cytogenetic features, [5, 6] such as a number of chromosomes, chromosome shape, and permissibility of crossing.

Christenson [7] defined the genus *Phalaenopsis* which consists of 62 original species. He divided the genus into five subgenera by morphological classification. Of these, two subgenera also were subdivided into four sections. He integrated the genus *Doritis*, which has been treated as an independent genus by other taxonomists, into the genus *Phalaenopsis* (section *Esmeralda*) in the broad sense (**Table 1**). He systematically described species characteristics, habitat, history of discovery, etc. in this work. Currently, his work is one of the most referenced in the classification of *Phalaenopsis* orchids.

#### *2.1.2 Molecular phylogenetic classification*

Differences in opinion on the importance of morphological features, such as pollen numbers caused disagreement among taxonomists. Therefore, molecular phylogenetic analyses based on DNA information independent from morphology have been actively studied. Molecular phylogenetic analysis [8–11] supports Christenson's proposal that the closely related genus *Doritis* and *Kingidium* should be included in the genus *Phalaenopsis* (section *Esmeralda* and subgenus *Aphyllae*, respectively). However, because there were many consequences that classifications under subgenera do not match his classifications, reexaminations were proposed. Although many results that genus *Doritis* is classified into genus *Phalaenopsis* are shown, some taxonomists proposed that genus *Doritis* should be used, considering the established *Phalaenopsis* intergeneric hybrids of *Doritaenopsis* in the past.

Recently, researchers reported that distantly related genera *Lesliea*, *Nothodoritis*, *Ornithochilus*, *Hygrochilus*, etc. should be included in the genus *Phalaenopsis* [11, 12]. In the genus *Phalaenopsis* subgenus *Hygrochilus*, a new species, *Phal*. *pingxiangensis* were discovered in China [13]. Due to proposals for revision of classification criteria based


*Applications of Biotechnological Approaches in the Product and Breeding of* Phalaenopsis*… DOI: http://dx.doi.org/10.5772/intechopen.104597*


#### **Table 1.**

*Classification of* Phalaenopsis*. Created with reference to Christenson [7].*

on the molecular phylogeny of *Phalaenopsis* and related genera, the classification of *Phalaenopsis* orchids will become more diverse than ever.

#### **2.2 Cultivars**

The registration system for new cultivars of Orchids was established by Sander (Sander's Complete List of Orchid Hybrids [14]), and now the Royal Horticultural Society in the United Kingdom (RHS) is taking over the system. Thus, the history of hybridization of orchid cultivars (horticultural varieties) can be traced to their original species. Today, the database of Sander's list makes it easy for us to search for the ratio of each original species constituting orchid hybrids.

Major cultivars on the current market of moth orchids are divided into two groups (standard or novelty) (**Figure 1**). Standard types include traditional cultivars with white, pink, semi-alba (white flower with a red lip), and striped big flowers. Novelty

*Applications of Biotechnological Approaches in the Product and Breeding of* Phalaenopsis*… DOI: http://dx.doi.org/10.5772/intechopen.104597*

#### **Figure 1.**

*Examples of cultivar types (standard, novelty).*

types include cultivars with new colorful flowers, such as red, orange, yellow, multiple flowers, flowers of dots (spotted) or mottle (harlequin), and flowers with fragrance. Phylogenetic analysis of recent most popular cultivars revealed their original species composition as ancestors of these hybrids [15]. In standard cultivars, original species of subgenus *Phalaenopsis* were the most important ancestors. Most white flower hybrids were the progeny of *Phal*. *amabilis*, *Phal*. *aphrodite*, *Phal*. *schilleriana*. The pink flower hybrids were progeny of *Phal*. *amabilis*, *Phal*. *schilleriana* and *Phal*. *sanderiana*. *Phal*. *equestris* and *Phal*. *stuartiana* was important for the creation of semialba and striped hybrid cultivars, respectively. In novelty cultivars, original species in such subgenus *Polycilos* other than subgenus *Phalaenopsis* were important ancestors. Of spotted/harlequin cultivars, the genetic contribution in the generation of red spots of the famous hybrid *Phal*. Golden Poker "Brother" was 25, 18.75, 12.5, and 6.25% from *Phal*. *gigantea*, *Phal*. *leuddemanniana*, *Phal*. *Amboinensis,* and *Phal*. *faciata*, respectively.
