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Patterns of xylem development: xylem in brown; arrows show direction of development from protoxylem to metaxylem. Xylem development can be described by four terms: centrarch, exarch, endarch and mesarch. As it develops in young plants, its nature changes from protoxylem to metaxylem (i.e. from first xylem to after xylem). The patterns in which ...
Land plants evolved from a group of freshwater green algae, perhaps as early as 850 mya, [3] but algae-like plants might have evolved as early as 1 billion years ago. [2] The closest living relatives of land plants are the charophytes, specifically Charales; if modern Charales are similar to the distant ancestors they share with land plants, this means that the land plants evolved from a ...
The fossil history of flowering plants records the development of flowers and other distinctive structures of the angiosperms, now the dominant group of plants on land.The history is controversial as flowering plants appear in great diversity in the Cretaceous, with scanty and debatable records before that, creating a puzzle for evolutionary biologists that Charles Darwin named an "abominable ...
The presence of vessels in xylem has been considered to be one of the key innovations that led to the success of the flowering plants. It was once thought that vessel elements were an evolutionary innovation of flowering plants, but their absence from some basal angiosperms and their presence in some members of the Gnetales suggest that this hypothesis must be re-examined; vessel elements in ...
The combination of one xylem and one phloem strand adjacent to each other is known as a vascular bundle. [14] The evolution of vascular tissue in plants allowed them to evolve to larger sizes than non-vascular plants, which lack these specialized conducting tissues and are thereby restricted to relatively small sizes.
The plant cuticle is one of a series of innovations, together with stomata, xylem and phloem and intercellular spaces in stem and later leaf mesophyll tissue, that plants evolved more than 450 million years ago during the transition between life in water and life on land. [11]
Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water. [citation needed] Non-vascular plants include two distantly related groups:
Herbchronology is the analysis of annual growth rings (or simply annual rings) in the secondary root xylem of perennial herbaceous plants. Similar seasonal patterns also occur in ice cores and in varves (layers of sediment deposition in a lake, river, or sea bed). The deposition pattern in the core will vary for a frozen-over lake versus an ice ...