Light microscopy survey of extant gymnosperm root protophloem and comparison with basal angiosperms
Bibliographic record
Abstract
Gymnosperm root protophloem is not well understood. There is a question as to whether root protophloem cells mature as phloem parenchyma, or as sieve elements, or if within the protophloem there is an anatomical and evolutionary gradient having characteristics of both cell types. This question is relevant to understanding anatomical and physiological mechanisms that supply nutrients to the root tip. Anatomical data from a broad range of species show that gymnosperms have one to three layers of parenchymatous protophloem cells located at the vascular cylinder periphery between the pericyle and the metaphloem. In some species, these cells are associated with secretory idioblasts. Near the root apex, protophloem cells develop a large central vacuole and, in transverse sections, their radial walls tend to be radially elongated. When mature, these cells are highly longitudinally elongated. Only these cells exhibit surging toward the root apex during chemical fixation. These data indicate that protophloem of gymnosperm roots lacks sieve elements. Because of its distinctive anatomical characteristics and the absence of sieve elements, gymnosperm root protophloem is a vegetative synapomorphy among extant species. The restriction of this tissue type to gymnosperms supports the hypothesis that it originated in a progenitor of that clade.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".