Proteals
Proteales is the name of a plant taxon located in the taxonomic category of order, belonging to the eudicotyledonous angiosperms (Eudicotyledoneae), among which they occupy a basal position. The circumscription of the group has varied greatly, and while Proteaceae (the type family) was always in it, in earlier classification systems such as Cronquist's (1981, 1988) the order was made up of very different families from those listed. recognize today. Both morphology analyzes and molecular DNA analyzes (on the rbcL, atpB and 18S rDNA sequences) support that Proteaceae together with Platanaceae and Nelumbonaceae form a clade, now recognized as Proteales (Chase et al. 1993, Hufford 1992, Manos et al. 1993, Soltis et al. 1997, 2000).
In modern plant classification systems (the APG III from 2009, the APWeb from 2001 onwards) the order is recognized as circumscribed by those families. But for example, in Cronquist's classification system, the most followed until a few years ago in the United States, the order was defined in a different way, including Proteaceae and Elaeagnaceae (family that includes Elaeagnus angustifolia, the tree of paradise).
Characters
Waxes of the epidermis with tubules (in 2 of the 3 circumscribed taxa), the main wax being nonacosan-10-ol; stipules around the stem (in 2 of the 3 circumscribed taxa); 1-2 pendulous ovules per carpel, with dry stigma, little is known about the development of the endosperm but it seems to be little or does not exist, the embryo is long.
At the date of publication of this article (August 2007) there is not enough information about the nodes, about the teeth of the leaves, about the seed coat or about the development of the endosperm.
For variations in pollen microsporogenesis and morphology, see Furness and Rudall (2004).
Diversity
The three families of the order are:
Family Proteaceae (type genus Protea). Trees of the tropical and temperate regions of the continental regions derived from Gondwana (Africa, Australia, South America, India). The Proteaceae produce large and showy inflorescences pollinated by the greatest diversity of animals, including small mammals. It includes notable genres such as Protea, Banksia, Grevillea, Hakea or Macadamia, which produces edible nuts. Many proteaceae are adapted to pollination by birds, which in the case of the Australian ones, will be mainly from the Meliphagidae family. Proteaceae are woody plants that can be recognized by the broad rays on the wood, the surface of which is wrinkled, the leaf-blades usually quite scleromorphic and coriaceous, with fairly toothed distant (or not) and a prominent reticulum, the base of the leaves enlarged, and the sometimes short petiole. The 4-mer flowers are usually aggregated in conspicuous inflorescences, the perianth may be monosymmetrical and curved, and the stamens are opposite to the perianth limbs, the single carpel usually with long style.
Family Platanaceae (type genus Platanus, the shade plane) trees of the Northern Hemisphere. Platanus x hispanica, a hybrid, is one of the most frequently planted shade trees in the Iberian Peninsula. Platanaceae is a very easy family to distinguish. The wood exfoliates in characteristic blades, the leaves have foliose stipules that completely surround the stem, the base of the petiole encloses the axillary shoot, and the blades have subpalmate venation. Platanus kerrii has a slightly different vegetative form from the other species, with stipules that are more or less scaly, an axillary shoot not enclosed by the petiole base, and pinnate venation. In all species, the inflorescences are globose and pollinated by the wind, and made up of numerous small flowers, the fruits are small achenes endowed with a pappus.
Family Nelumbonaceae (type genus Nelumbo), aquatic plants called lotuses or water lilies, although they are not particularly related to the water lilies of the Nymphaeaceae family. Nelumbonaceae are easily recognized by their peltate leaves with mainly dichotomous venation, which are held above the water like parasols, and their flowers, which are similar to those of nymphs but have free carpels embedded in a large, obconic receptacle.
Phylogeny
- Theoretical Introduction in Philogenia
Chase et al. (1993) and Drinnan et al. (1994) found the Platanaceae and Nelumbonaceae to be sister clades, although Barthlott et al. (1996) found that the cuticle waxes of Platanaceae and Nelumbonaceae were very different. Although the order is small, it looks uncomfortably heterogeneous; although it has moderate support from molecular DNA analyzes (APG 1998, APG II 2003, Chase et al. 1993, Hufford 1992, Manos et al. 1993, Soltis et al. 1997, 2000). Hayes et al. (2000) emphasize that there are only 2 sepals in Nelumbo, and possibly the entire order can be characterized as having dimerous flowers (see Doyle and Endress 2000). for Proteaceae).
Taxonomy
- Theoretical Introduction in Taxonomy
Synonyms: Nelumbonales Willkommen and Lange, Platanales J. H. Schaffner, Proteanae Takhtajan, Nelumbonanae Reveal, Nelumbonidae Takhtajan, Nelumbonopsida Endlicher, Proteopsida Bartling.
Circumscription sensu APG III and APWeb: 3 families, 82 genera, 1,610 species.
- Proteaceae
- Platanaceae
- Nelumbonaceae
Proteales being an order of basal eudicots (ie, not belonging to the class Gunneridae).
The previous ones coincide with this constituency: APG II 2003, APG 1998.
Thorne (2007) includes the order, several times divided, with Sabiales and Buxales, in his heterogeneous Ranunculidae.
Nelumbonaceae used to be associated with Nymphaeaceae, because the two had superficially similar flowers and bodies, both being aquatic. Takhtajan (1997) removed Nelumbonaceae from the neighborhood of Nymphaeales, but considered it a very isolated group and placed it within its own subclass Nelumbonidae.
Evolution
Both Nelumbonaceae and Platanaceae have fossils from the Albian (late Early Cretaceous, dated to about 106 and 110 million years ago respectively, see Upchurch and Wolfe 2005).
Anderson et al. (2005), using fossil and molecular data, date all extinct fossil relatives before the appearance of living groups (what in paleontology would be called the &# 34;trunk group" Platanales) in about 121-119 million years, the divergence would have started 121-115 million years ago. At least from a molecular point of view, both Platanus and Nelumbo can be considered living fossils (Sanderson and Doyle 2001).