What is Suksdorf’s hawthorn? Revision of the Western North American 20-stamen black-fruited hawthorns (Crataegus series Douglasianae, Rosaceae subtribe Malinae)
Bibliographic record
Abstract
An agamic complex of 20- and 10-stamen, black-fruited hawthorns (Crataegus subg. Sanguineae, sect. Douglasianae) occurs in western North America, with a 10-stamen taxon disjunct in the upper Great Lakes basin. Here, we recircumscribe the 20-stamen taxa at the core of this complex (C. ser. Douglasianae). This is needed in order to distinguish between a presumptively ancestral diploid and its allo- and autopolyploid derivatives, all differing in breeding system, distribution, morphology, and pattern of genetic variation. The earliest name for these 20-stamen taxa, Crataegus gaylussacia A. Heller, was given to distinctive plants of Marin and Sonoma counties in California that have recently been shown to be autotriploids. In Flora North America, however, this name was applied to all 20-stamen, black-fruited hawthorns. We recircumscribe C. gaylussacia, and also recircumscribe and typify a slightly younger name, C. suksdorfii (Sarg.) Kruschke, with a specimen from southern Washington with the diminished pollen fertility found in allopolyploid, apomictic black-fruited hawthorns occurring east of the Cascades, from northern California north to southernmost Alaska. Finally, we recognize the diploid, self-incompatible, sexual black-fruited hawthorns found west of the Cascades from northern California to southwestern Washington as Crataegus rhodamae-loveae sp. nov. Together with the 10-stamen, black-fruited hawthorns in predominantly tetraploid, apomictic, and self-fertile C. douglasii Lindl. and its segregates (discussed in detail in a companion paper), these species are linked by whole genome duplications associated in most cases with hybridization, with members of red-fruited C. subg. Americanae, and with each other. We suggest that this complex provides a model for understanding other such groups of Crataegus species that are related by whole genome duplications resulting from the fertilization of unreduced gametes (facilitated by but not necessarily dependent on occurrence of gametophytic apomixis), often together with hybridization. We note that an earlier effort at DNA barcoding these and other hawthorn species that provided limited support for our taxonomic decisions here also demonstrated some limited utility of the original plant DNA barcoding loci in groups like Crataegus. The taxonomic decisions we advocate will warrant consideration when other groups of hawthorns are revised in the light of data like those employed here.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.003 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".