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Is Welwitschia really that important?[edit]

I'm amazed that Welwitschia is mentioned in the introduction. The information is technically correct, but this is a single species with limited distribution, so maybe doesn't warrant this level of attention? Cfs14 (talk) 18:30, 14 February 2010 (UTC)

Lifespan of evergreen trees' leaves[edit]

I have corrected the misconception that leaves on evergreen trees always persist for at least a year. The section on reasons for being evergreen is missing some information, although the material there is largely correct.Cfs14 22:23, 11 June 2007 (UTC)

Somebody should add to the explanation of why they are evergreens. Do they just rely on photosynthesis less than other plants, so they can get nutrients from the ground when it is too cold and dark for it? Then why are they "ever green"? wouldn't they have fewer chloroplasts?

Some sources that confirm both ends of the months-to-decades range of the "leaf life span (LLS)" of evergreens, as it's called in botany ---
  • Leaves, Primary Plant Body, Leaf Anatomy section:
"Life Expectancy
Deciduous < 1 year
Evergreen > 1 year (usually < 5 years)"
Botany online - The Internet Hypertextbook
International Edition - Contents
  • In Abstract section: "While many evergreen herbs have a leaf longevity of more than 1 year, some species have leaf longevities shorter than 1 year. The latter species have leaf flushes in spring (summer leaves) and in autumn (winter leaves) and maintain their shoots as evergreen. Such leaf phenology has been termed as dimorphic (Givnish, 1987), heteroptic (Uemura, 1994), or evergreen shoot with deciduous leaves (Yoshie, 1995)."
In Materials and Methods, Species section: "Viola hondoensis (Violaceae) is one of the species that have evergreen shoots with a short-lived leaf. It is generally found in the understory of deciduous temperate forests in Japan and Korea. Its summer leaves are produced in spring and shed in autumn, whereas winter leaves are produced in autumn and shed in spring (Mishio, 1995)."
"Why does Viola hondoensis (Violaceae) shed its winter leaves in spring?"
Kouki Hikosaka, Yoshie Kawauchi and Takahide Kurosawa
American Journal of Botany
Published online: 15 November 2010
Printed: December 2010 vol. 97, no. 12, 1944-1950
DOI: 10.3732/ajb.1000045
  • In Abstract section: "The mean leaf life span determined for Araucaria araucana (24 years) is among the highest figures reported for any plant species."
In Results, Leaf life spans section: "Mean leaf life spans ranged from ca. 3 years in Podocarpus saligna to ca. 24 years in Araucaria araucana (Table 1). Leaf life span of A. araucana was significantly influenced by light environment, the mean for shaded individuals being > 20 % higher than that for well-lit trees (Student t-test, P = 0.01, Table 1)."
"Leaf life spans of some conifers of the temperate forests of South America"
Christopher H. Lusk
Revista Chilena De Historia Natural, vol. 74, no. 3, 2001
  • The Majestic Basin and Range..., Did You Know? section: "Many of Great Basin National Park's bristlecone pines were growing at the time the Egyptians were building the pyramids. Not only are the trees themselves old, but the needles alone ::can be 25-40 yrs old!"
Great Basin National Park, National Park Service
All the best, Wordreader (talk) 04:59, 31 August 2013 (UTC)

Hard to understand[edit]

In cool temperate climates, fewer plants are evergreen, with a predominance of conifers, as few evergreen broadleaf plants can tolerate severe cold below about -25 °C. Ufwuct 23:21, 8 January 2007 (UTC)

"Different trees shed their leaves at different times, so the forest as a whole looks green."[edit]

I have never seen an evergreen tree with no needles/leaves, but this sentence in the first paragraph implies that that is how it works in general with evergreen trees.