Abstract
Predictions from a mechanical model for hollow vertical stems are tested against morphometric and mechanical studies of the vertical stems of Equisetum hyemale. The model predicts 1) that the wall thickness of hollow internodes must be at least 15% of the external radius of shoots, 2) that the elastic modulus of stems is quantitatively related to the ratio of apoplast (cell walls) to symplast (cytoplasm) areas in transverse sections through stems, and that (3) hollow stems are designed to sustain an additional and significant proportion of their own weight. The "safety factors" predicted for a hollow vertical stem are used to examine two adaptationist explanations for hollow stems: 1) "economy in design," which argues that natural selection will favor a reduction in the metabolic cost in constructing an organ, and 2) "mechanical design," which argues that stems are designed to maximize their mechanical stability during vertical growth. Evidence from E. hyemale indicates that 1) there is a developmental limit to the maximum allotment of biomass invested in the construction of stems, 2) as stem height increases, morphometric adjustments in internodal wall thickness occur which converge on predicted safety limits, and 3) the elastic modulus of stems changes as a function of the ratio of apoplast to symplast areas seen in transverse sections through shoots. Biomechanical and developmental evidence and the allometry of E. hyemale stems are consistent with the view that stems are designed for safety and are inconsistent with some predictions based on the economy in design.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 6
Claim · model-written summary
The model predicts that the wall thickness of hollow internodes must be at least 15% of the external shoot radius.
- Taxon
- Equisetum hyemale
%2C_jard%C3%ADn_bot%C3%A1nico_alpino-%C3%A1rtico%2C_Troms%C3%B8%2C_Noruega%2C_2019-09-04%2C_DD_81.jpg?width=60)
Equisetum hyemalee0 - Outcome
- wall thickness of hollow internodese1
- Value
- 15% of the external radius of shootse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
%2C_jard%C3%ADn_bot%C3%A1nico_alpino-%C3%A1rtico%2C_Troms%C3%B8%2C_Noruega%2C_2019-09-04%2C_DD_81.jpg?width=500)
Verbatim
e0“vertical stems of Equisetum hyemale”
e1“the wall thickness of hollow internodes must be at least 15% of the external radius of shoots”
Claim · model-written summary
The model predicts that hollow stems sustain an additional proportion of their own weight.
- Taxon
- Equisetum hyemaleEquisetum hyemalee0
- Outcome
- proportion of their own weighte2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“vertical stems of Equisetum hyemale”
e2“hollow stems are designed to sustain an additional and significant proportion of their own weight”
Claim · model-written summary
Internodal wall thickness is adjusted with increasing stem height, converging on predicted safety limits.
- Taxon
- Equisetum hyemaleEquisetum hyemalee0
- Outcome
- morphometric adjustments in internodal wall thicknesse3
- Qualifier
- as stem height increasese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“vertical stems of Equisetum hyemale”
e3“as stem height increases, morphometric adjustments in internodal wall thickness occur which converge on predicted safety limits”
Claim · model-written summary
The elastic modulus of stems changes with the ratio of apoplast to symplast areas in transverse sections.
- Taxon
- Equisetum hyemaleEquisetum hyemalee0
- Organ / stage
- shootse4
- Outcome
- elastic modulus of stemse4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“vertical stems of Equisetum hyemale”
e4“the elastic modulus of stems changes as a function of the ratio of apoplast to symplast areas seen in transverse sections through shoots”
Claim · model-written summary
There is a developmental limit to the maximum biomass allotted to stem construction.
- Taxon
- Equisetum hyemaleEquisetum hyemalee0
- Outcome
- maximum allotment of biomass invested in the construction of stemse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“vertical stems of Equisetum hyemale”
e5“there is a developmental limit to the maximum allotment of biomass invested in the construction of stems”
Claim · model-written summary
Hollow stems are designed for safety rather than economy in construction.
- Taxon
- Equisetum hyemaleEquisetum hyemalee0
- Outcome
- stems are designed for safetye6
- Qualifier
- Biomechanical and developmental evidencee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“vertical stems of Equisetum hyemale”
e6“stems are designed for safety and are inconsistent with some predictions based on the economy in design”
e7“Biomechanical and developmental evidence and the allometry of E. hyemale stems”