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 Malus sikkimensis fruit
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Amelanchier - serviceberry, juneberry |
The Maloideae (apple subfamily) is a large subfamily of the rose family Rosaceae with 28 genera, including approximately 1100 species worldwide with most species occurring in the temperate Northern Hemisphere. It is sometimes placed in its own family the Malaceae [1]
This subfamily consists of shrubs and small trees characterised in its traditional description by the possession of a pome, a type of accessory fruit, and by a basal haploid chromosome count of 17 (instead of 7, 8, or 9 as in the other subfamilies). The (mostly) syncarpous flowers of the plants in this subfamily have two to five carpels, which are fused to each other and to the hypanthium (floral cup). However, they exhibit a considerable variation in this respect. The ovary is at least three-quarters inferior and matures into the pome fruit.
These features distinguish partly this subfamily from the other subfamilies in the Rosaceae, where the carpels are free or solitary and the ovary superior. Partly, because the flowers in the genera Cotoneaster, Heteromeles, and Pyracantha are completely apocarpous (with carpels free from each other), while the genus Dichotomanthes is perigynous (sepals, petals and stamens around the edge of the ovary) and has a superior ovary.
The pome is a fruit type unique to this subfamily. It grows through swelling of the adnate hypanthium. The leaves of the plants in this subfamily are evergreen to deciduous. These leaves come in a wide variety of shapes from simple leaves with entire, toothed or pinnately lobed margins to pinnately compound leaves.They can be thin and membranaceous or even coriaceous (having a leathery texture).
More recent taxonomic proposals expand Maloideae to include four herbaceous genera that are more closely related to the traditional Maloideae than to other species of Rosaceae. These are Kageneckia, Lindleya, and Vauquelinia, which have a haploid chromosome count of 15 or 17 but bear fruits that are capsules, and Gillenia, which has a haploid chromosome count of 9.
The genus Sorbus s.l. has been found polyphyletic and has been split into five genera : Sorbus sens. str., Cormus, Chamaemespilus, Aria and Torminalis. Eriolobus and Docyniopsis are distinct from Malus. On the other hand Micromeles has been included in Aria, and Stranvaesia and Aronia included in Photinia. [2]
The group includes a number of plants bearing commercially important fruits, such as apples and pears, while others are cultivated as ornamentals.
Notes
- ^ GRIN Taxonomy for Plants
- ^ Kenneth R. Robinson, James B. Phipps, Josdeph R. Rohrer (1992). "Summary of the leaves in the genera of Maloideae (Rosaceae)". Annals if the Missouri Botanical Garden 79 (1): 81–94. doi:.
References
- Joseph R. Rohrer, Kenneth R. Robinson, James B. Phipps - Floral Morphology of Maloideae (Rosaceae) and its systematic Relevance; American Journal of Botany, 81 (5), P. 574-581; 1994
Wikipedia content modification information:
- This page was last modified on 7 October 2008, at 15:04.
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