Arctostaphylos

A working post. Continually updated.

This post primarily focuses on Arctostaphylos near Monterey, California.

Please consider intellectual property before re-using any original content here. I'm working toward journal paper that involves some of the ideas. Acknowledgements: Keith, Alex, Yerba, Henrik, Paul, Morgan and others with whom I've communicated about Arctostaphylos on iNat.

Taxonomic organization of the Arctostaphylos genus

Knowing how species within the genus are grouped helps with wrapping one's mind around the numerous taxa that can sometimes co-occur. There are three main groups (Boykin et al. 2005, Wahlert et al. 2009, Parker et al. 2020), and generally, taxa within the same group do not densely co-occur (Parker et al. 2020). The three main groups are: 'small clade' diploids, 'large clade' diploids, and 'large clade' tetraploids. The small clade is so named because it has a smaller number of taxa - about 18, compared with 87 in the large clade, 2 of unknown clade, and 1 named hybrid. Within the large clade, there are 52 diploids and 35 tetraploids and many of the tetraploid taxa in particular are subspecies. (There are also outliers to the three main groups: a small clade tetraploid, perhaps two species that occur as both diploids and tetralpoids, and two tetraploids for which the clade affiliation is not yet known)

The 'groups' above are informal divisions; they are not yet formal 'sections' within the genus. There were previous attempts to divide the genus formally (e.g. Roof, 1970s, as cited by Keeley et al. 2017; Wells 1992, 1993, 2000. But these divisions are not used in subsequent presentations of the genus (e.g. Parker et al. 2007) and they do not align with the contemporary, genetically-based groupings (Boykin et al. 2005, Wahlert et al. 2009, Parker et al. 2020).

I like to use abbreviations for the three groups: S2, L2, and L4.

Arctostaphylos observations on Fort Ord and nearby

More detail on selected taxa

Small-clade diploids (S2)

Burl absent.

Arctostaphylos hookeri ssp. hookeri

A. hookeri is the only member of it's group in the Monterey Area. It does its own thing.

Large-clade diploids (L2)

Burl absent.

Each large-clade diploid species keeps mainly to itself. The notable exceptions are pumila and montereyensis; each has it's own broad geographic region of exclusivity within the L2 group; but there's also a specific zone of interface that I'm mapping out in detail. There's also overlap between the Fort Ord pajaroensis and montereyensis, but not at particularly high densities. I haven't noticed any overlap between the other L2s, e.g. pungens and hookeri, or pumila and edmundsii.

Arctostaphylos pumila

Stem prostrate. Leaves wider distally (unlike edmundsii), tomentose abaxially (unlike edmundsii). Coastal, centered on Fort Ord.

See also 'tall pumila', below.

Notable observations:

Arctostaphylos montereyensis

Stem erect. Leaves isofacial, glabrous, erect. Toro Park and eastern Fort Ord

Arctostaphylos pajaroensis

Stem erect. Leaves bifacial, basally lobed, short-petioled. Pajaro Hills (e.g. Manzanita County Park) with a small region of outliers in northern Fort Ord

Arctostaphylos edmundsii

Stem prostrate. Leaves glabrous abaxially(unlike pumila) and widest more proximally than pumila. Not on Fort Ord. Occurs in Big Sur, right on the coast

Arctostaphylos glauca

Stem erect. Leaves glaucous. Not on Fort Ord. Occurs in inland.

Arctostaphylos pungens

Stem erect. Leaves green (unlike glauca). Nascent inflorescence club-like on long axis (unlike hookeri). Not on Fort Ord. Occurs inland.

Arctostaphylos gabilanensis

Stem erect. Leaves isofacial (unlike pajaroensis), short-petioled, green (unlike glauca). Not on Fort Ord. Occurs inland.

Potential hybrids within the large diploid clade

Large-clade tetraploids (L4)

Burl present. Sometimes the burl is obvious. Many times not. A little crawling and scratching is sometimes helpful.

Arctostaphylos tomentosa

Leaves bifacial.

The definitive character for A. tomentosa is: "Old stem bark persistent, gray, shredding" (Parker et al. in Jepson). It's important to note the word "old" here. Many small and medium-sized plants cannot be reliably identified because they do not exhibit sufficiently "old" stems. While some A. tomentosa have gray-shreddiness on stems of all ages, many (at least in Fort Ord) have young stems that are smooth, and old stems that are rough.

For more on this, see below under "good reference points for the range of variation in old stem bark".

Arctostaphylos tomentosa ssp. tomentosa

Twig hairs short only. Leaves tomentose abaxially.

This is usually a pretty straightforward taxon to identify on Fort Ord and the Monterey Peninsula if you have a photo of twig and leaf underside, because no other short-twig-haired abaxially-tomentose burl-formers are yet known from this region. Further south toward Big Sur, you would need to consider other short-twig-haired taxa like cushingiana, rosei, and maybe eastwoodiana- depending on how well your photo showed the abaxial leaf surface.

There's an idea that A. tomentosa have a notable propensity for above-ground burls e.g.:
-- https://www.inaturalist.org/observations/197637269 Morse Preserve

Arctostaphylos tomentosa ssp. bracteosa

Old stem rough. Twig hairs short and long, glandular.

Interesting observations or discussions about A. t. bracteosa
Arctostaphylos tomentosa ssp. hebeclada

Leaf abaxially glabrous, or at least less than fully tomentose.

Distribution centered on the Monterey Peninsula (Jacks Peak), although two putative hebeclada have been documented in eastern Fort Ord:
- https://www.inaturalist.org/observations/146865033 Crescent Bluff Rd
- https://www.inaturalist.org/observations/196089660 Trail 36 (nr Jacks Rd / Engineer Saddle)

Taxonomic history of Arctostaphylos tomentosa ssp. hebeclada

Best seen at Jacks Peak. Not well-knowm at Fort Ord, but here's two candidates:

Arctostaphylos tomentosa ssp. hebeclada can have hairier leaf undersides than the most recent literature (incorrectly, in my opinion) suggests. Arctostaphylos tomentosa ssp. hebeclada is known in the contemporary literature as the subspecies with the glabrous abaxial side of the leaves (and no long twig hairs). Interestingly, the simple "glabrous abaxially" description only appeared very recently, in 2009. Prior to 2009, the description had been consistently more hirsute from the moment it was first described under species tomentosa in 1940. Particularly odd is that the switch happened in the dead of night, so to speak, between Parker et al.'s peer-reviewed journal revision of the genus, and the same authors' treatment in Flora of North America. From memory, it is not uncommon for FNA to be more brief than state and regional keys. So it seems plausible that hebeclada lost its hairs in the literature merely as an editorial consequence. There does not seem to be any evidence that the switch was motivated by an actual re-examination of specimens or of fresh collections.

Given that the current keys leave a gap between "glabrous" and "tomentose", and that all historic keys that have encompassed the contents of the gap did so with hebeclada, I think it is reasonable to conclude that a less-than-fully tomentose specimen qualifies more as hebeclada than ssp. tomentosa i.e. specimens deserving any of the qualifiers used prior to 2009 i.e. : "nearly glabrous", "tomentulose", "puberulent", "glabrate", or "sparsely pubescent".

Here's the history:

- 1833 (Douglas) - First collected
- 1839 (De Candolle) - First described, but as one of two varieties (trichclada and hebeclada) in a species called Andromeda bracteosa. In this context, abaxial leaf hairs were not mentioned because, adjacent to bracteosa, only the glandular hairs needed to be addressed.
- 1934 (Eastwood) - Moved genus from Andromeda into Arctostaphylos, but still as a variety of bracteosa, and thus abaxial leaf hairs not relevant nor mentioned.
- 1939 (Adams) - Dissertation, succeeded in 1940 by a journal publication (see below). Not seen yet. McMinn saw it, and referenced it in Arctostaphylos species descriptions.
- 1939 (McMinn) - Book. Leaves "tomentulose, puberulent, or nearly glabrous beneath". McMinn is almost certainly borrowing this text from Adams' 1939 dissertation, which I have not seen.
- 1940 (Adams) - Moved into species tomentosa for the first time in a journal publication (but see McMinn, above), creating the first need to address abaxial leaf hairs as the basis of difference with the nominate variety. Thus, hebeclada abaxial leaf surface defined for the first time by: "nearly glabrous to a tomentulose condition" and "glabrous, puberulent, or tomentulose".
- 1958 (Munz) - "glabrate to tomentulose beneath"
- 1993 (Wells) - "glabrate to tomentulose beneath"
- 2007 (Parker et al.) - "glabrous or sparsely pubescent"
- 2009 (Parker et al.) - "glabrous abaxially". To me, this is an error resulting from brevity - to drop the possibility of any pubescence without any apparent re-examination of specimens or re-treatment of the genus.
- 2012 (Parker et al.) - "glabrous abaxially"
- 2015 (Kauffmann et al.) - "glabrous abaxially"

Note to self: need to look at "hebeclada" at Jacks with long non-glandular twig hairs.

Arctostaphylos tomentosa ssp. daciticola

Old stem rough. Twig hairs short and long, non-glandular.

A. t. daciticola is a rare taxon that is generally understood to be restricted to the Morro Bay region. I've found a quite few plants on Fort Ord that key out to daciticola, e.g..
- A. t. daciticola on the eastern margin of Fort Ord Good discussion in the comments.
- A. t. daciticola in central northern Fort Ord
- A. t. daciticola 20 feet from the one above
- A. t. daciticola about 2000 feet from 8th & Gigling

Arctostaphylos tomentosa that don't quite fit

Of the various plausible combinations of long twig hairs, glands, and abaxial leaf vestiture, there's one combination of characters in species tomentosa that I think is plausible, but hasn't yet been described. I think I'm seeing it occasionally on Fort Ord. It's a (1) burl-former, with (2) old stem bark that is persistent, gray, shredding, (3) abaxial leaf surfaces that are glabrous or nearly so, (4) long twig hairs, and maybe cryptic glands.. It differs from four other subspecies by only a single character. Thus, it's like a bracteosa (the sub-glabrous version) without glands, or a hebeclada with long twig hairs, or a daciticola with glabrous leaf undersides, or a ssp. crustacea with shreddy bark.

Arctostaphylos crustacea

Leaves bifacial. The definitive character for distinguishing Fort Ord crustacea from tomentosa is: "Old stem smooth or peeling, +- red" (Parker et al. in Jepson). The key word here is "old". If you don't have old stems, you cannot reliably ID a smooth-stemmed plant as A. crustacea.

For more on this, see below under "good reference points for the range of variation in old stem bark".

In my experience, clearly identified A. crustacea on Fort Ord are limited to the eastern corner. To be undisputable - in my opinion - there needs to be large, undamaged stems that are "smooth or peeling, +- red". By "very large", I mean somewhere in the region of 8 cm to 10 cm diameter or larger. The literature never specifies this and type specimens never (?) recorded it. So we are left to interpret it. If we allow stems smaller than, say, 6 cm to define crustacea, this results in too much overlap between crustacea and tomentosa under the allopatry hypothesis of Parker et al. (2021). So, smooth stems less than about 6 cm in A. tomentosa areas are probably not A. crustacea.

Arctostaphylos crustacea ssp. crustacea

Twig with long twig hairs (that are generally non-glandular). Leaves glabrous abaxially.

In eastern Fort Ord, a long-twig-haired abaxially-glabrous-leaved burl former is very likely to be A. crustacea ssp. crustacea. Although, if any gray-shreddy stems are in the immediate vicinity, one might also consider a cryptic-glanded A. tomentosa ssp. bracteosa.

In western Fort Ord, I'm skeptical that any A. crustacea ssp. crustacea occur west of Hennekens Ranch Rd. Unless the stem is large and smooth, A. tomentosa ssp. bracteosa can't easily be ruled out unless glands have been ruled out with a macro lens or better.

Arctostaphylos crustacea ssp. crinita

Twig with long hairs (that are generally non-glandular). Leaves tomentose abaxially.

In my opinion, the westward extent of A. crustacea ssp. crinita may have at times been over-stated due to a tendency to want to identify plants to species level or better. The reality is that smooth bark on small to medium stems on Fort Ord is inconclusive, even if there are long twig hairs. Such a plant could be either: (1) A. crustacea ssp. crinita, (2) A. tomentosa ssp. bracteosa too with stems that are not "old" enough to reliably exhibit bark that is "persistent, gray, shredding", and with glands that weakly expressed and too small to be seen with typical optics, or even (3) A. tomentosa. ssp. daciticola.

Taxonomic history of Arctostaphylos crustacea ssp. crinita
  • McMinn (1939) is the first publication of crinita, specifically as. A. t. var. crinita, with "long spreading bristle-like hairs" and an illustration of the same.
  • McMinn referred to Adams work as "Ms" i.e. still in manuscript form (presumably a dissertation) and not yet published.
  • Adams (1940 journal publication) gave it a different name - A. c. var. tomentosiformis, "with spreading white bristly hairs;". There doesn't appear to be an explanation for why Adams seems to have changed epithets (from crinita to tomentosiformis) and species (from tomentosa to crustacea) between the manuscript version that McMinn had access to (1939) and the published version (1940). As seen below, the taxon has wavered a few times between species tomentosa and species crustacea (because it is generally viewed as being somewhat intermediate between the two).
  • Wells (1968) was the next major treatment, and he combined McMinn's and Adams' (and also Munz's) nomenclature to yield A. t. ssp. tomentosiformis.
  • Munz (1959) went with A. t. var. tomentosiformis in a state-wide flora.
  • Gankin (1971) noted the mix-up with the names and that McMinn should prevail. But Gaskin also noted something quite interesting: insulicola in the Channel Islands sometimes have long setose hairs. On this basis, Gankin argued that the insulicola should be regarded as crinita, much farther south than where crinita had previously been described. One thing we can take from this is that the long hairs have been regarded as definitive for crinita, not merely incidental.
  • Wells (1987) seems to have recognized Gankin (according to Parker et al. 2007). But I don't have Wells (1987) yet; it's a hard one to get.
  • Wells stayed the crinita course in his 1993 Jepson treatment (under a lumped species tomentosa that included what we now separate out under species crustacea), still with "long, white bristles".
  • Then came Parker et al. (2007), which is essentially the treatment we live by today. They flipped it to A. c. ssp. crinita, but still "with long, non-glandular bristles above a short pubescence".
Interesting observations or discussions about A. c. crinita
Arctostaphylos crustacea ssp. rosei

Old stem smooth. Twig with short hairs only. Leaves abaxially glabrous (but see notes below). Pedicel, ovary generally short-nonglandular-hairy.

Perhaps the first thing to know about rosei is that it's distribution appears to have been grossly over-stated, owing to a divergence in the literature that originated with an article by Roof in 1964. The upshot is that, as far as I have been able to determine, no verifiable records exist of the taxon currently described as rosei anywhere beyond its type locality at Lake Merced in San Francisco. If you know of one, let me know; it would need to have evidence of an old stem with bark that is generally smooth or peeling. I've studied all the iNat records, all the CCH sheets that have been digitized, and all the literature, and while that study is still in progress, I'm pretty sure the outcome is that there's zero verifiable evidence of rosei other than at the type locality. And even the standing of the type population is questionable, potentially being more properly considered as a northern outlier of hebeclada.

The story is complicated. In a nutshell, Roof (1964) proposed synonymizing rosei and hebeclada under species rosei, but Roof's proposal was never accepted. Despite this, shortly after Roof's publication, historical CCH sheets in Monterey County were changed to rosei, and new and recent collections of "rosei" in Monterey County were labelled as such. The Field Guide (Kauffmann et al., two editions) published range maps of rosei in Monterey County based in part on the locations of the CCH sheets labelled rosei. However, all of this is predicated on Roof's proposal, which was never accepted in any other publication. There was a divergence. The published literature continued to recognize rosei and hebclada as separate taxa. But the CCH records and the maps in the Field Guide persist as a relic of Roof's position. For a time, iNaturalist records were identified as "rosei" in Monterey County. But on closer examination, none have been found that clearly match the current taxonomic description of the taxon.

The story is ongoing and not fully resolved.

Taxonomic history of leaf vestiture in Arctostaphylos crustacea ssp. rosei

This section was written a while ago, before the idea emerged that rosei barely exists, if at all.

Arctostaphylos crustacea ssp. rosei is another taxon (like hebeclada) where the main contemporary diagnostic character is not the same as the main original diagnostic character, because of the genus-level reorganizations that have occurred. Thus, the contemporary focus on abaxial leaf hairs was not particularly relevant in the original literature, nor even mentioned in some cases.

Arctostaphylos crustacea ssp. rosei was first described by Eastwood in 1933 as Arctostaphylos rosei, with "dorsal" (adaxial) leaf hairs mentioned, but abaxial leaf hairs not mentioned. It was first included in a key a year later, where Eastwood (1934) placed it adjacent to Arctostaphylos crustacea, separable by presence of bristly-hairs on the stem - not mentioning leaf hairs at all, nor needing to mention them particularly. McMinn moved it to a variety of cructacea in 1939, but this didn't change how it needed to be keyed e.g. by Adams in 1940 or Munz in 1959.

The first time the abaxial leaf hairs needed to be mentioned was in Wells' 1968 revision of the genus, where everything was lumped under tomentosa. Thus, compared to insulicola, rosei had "glabrous" leaves in 1968. Wells refined this in his 1994 Jepson treament to "lower lf surface +/- glabrous" - i.e. some hairs allowed.

Most recently, the Parker et al. revision and subsequent publications have stuck with just "glabrous" (2007, 2009 in FNA, 2021 in the Kauffmann et al. book).

Thus, the hairiest interpretation of the abaxial leaf of a rosei in the literature is "+/- glabrous".

Could a Monterey County ssp. rosei grade into a ssp. insulicola? Perhaps. Intergradation is often postulated for this group - e.g. by Wells (1968). Subspecies insulicola is generally restricted to the Channel Islands, but exceptions are noted. Parker et al. (2007) state "some individuals have been found in the southern Santa Cruz Mountains". CalFlora has five collections by Jeff Bisbee at Tilden Park just east of Berkeley. I've observed several putative insulicola in Monterey County (see links in the section below).

Arctostaphylos crustacea ssp. insulicola

(Old stem smooth. Short hairs only. Abaxially tomentose.)

Arctostaphylos crustacea ssp. subcordata

(Old stem smooth. Densely glandular hairy.)

Arctostaphylos crustacea / tomentosa complex unnamed combinations: U1 and U2

There are 12 possible combinations of the four major characters in the tomentosa/complex. Two of them are unnamed. I call them U1 and U2. I'm pretty convinced U1 exists. U2 is still a work in progress.

U1: Gray-shreddy, long-twig-haired, non-glandular, abaxially glabrous. Like daciticola but abaxially glabrous. Like hebeclada, but glandular. Like ssp. crustacea but gray-shreddy.

  • Links coming soon.

U2: Smooth-barked, long-twig-haired, glandular, abaxially glabrous. Like subcordata but abaxially glabrous. Like ssp. crustacea but glandular. Like bracteosa next to it but smooth-barked.

Arctostaphylos glandulosa

Leaves isofacial. These are tough to find on Fort Ord, because isofacial burl-former leaves don't exactly jump out at you from the chaparral. Several times I've need a compound microscope to resolve uncertainty. Furthermore, the isofacial:bifacial character is not a dichotomy. To be precise, one really needs to quantify the ratio of adaxial stomates to abaxial stomates. A value of 0.0 is bifacial. A value of 1.0 is the highest likely. But values as low as 0.37 have been published as sufficiently high to be considered to be on the isofacial end of the gradient (Keely et al. 2009, Table 2).

Arctostaphylos glandulosa ssp. glandulosa

Occurs on Fort Ord.

Note to self: Need to work up notes on the apparently bifacial "glandulosa" population at Garland.

Arctostaphylos glandulosa ssp. howelli

Big Sur, generally on the coast side.

Arctostaphylos glandulosa ssp. cushingiana

Big Sur, generally on the inland side.

Potential diploid x tetraploid hybrids within the large clade

(Need some discussion here. Should referece parryana & uva-ursi.)

Arctostaphylos pumila x tomentosa

Arctostaphylos montereyensis x tomentosa ?

-- https://www.inaturalist.org/observations/197855079 ???

Arctostaphylos montereyensis x crustacea

-- https://www.inaturalist.org/observations/196393775 Hobbit Trail in central northern Fort Ord (my internal FID: 3267 & 3264).

Interesting observations with unresolved identification

Notes on mophological characters

Need large stems to reliably distinguish A. tomentosa from A. crustacea

How large? About 6 cm to 10 cm. I'll make a list of observations here to underscore this point.

Observations with images that provide good reference points for the range of variation in old stem bark

Branch-like structure in long setose hairs

Are glandular secretions sometimes only seasonally evident?

Microscope images of glandular secretions, or not

- Glandular secretions clearly evident
-- https://www.inaturalist.org/observations/147658681 Clear to amber
-- https://www.inaturalist.org/observations/146727002 Amber
-- https://www.inaturalist.org/observations/195975891 Dark (appearing black under hand lens)
- Glandular secretions not clearly evident
-- https://www.inaturalist.org/observations/146312734

Variation in ratio of adaxial to abaxial stomates in tetraploids

Zero or low ratios are exhibited by A. tomentosa and A. crustacea.
High ratios are exhibited by A. glandulosa.

Microscope images of leaf hairs

Confirmation bias






Publicado el 17 de diciembre de 2023 a las 05:41 PM por fredwatson fredwatson

Comentarios

Wow! There's a lot of good stuff here, and it is a bit of a marathon read, so I'll have to come back now and again to reference it periodically to get a better handle on all that you've put together.

One thing I'd comment on preliminarily would be the clades determined by ploidy. A few questions:

1) is 'large' vs 'small' clade a description of the number of species in each clade, or a descriptor of something else?

2) how do people measure ploidy? It's a really basic question, but I wonder if you need specialized equipment beyond DNA stain and a microscope, or is it only by more specialized processes (Electron microscopy or gel electrophoresis, etc.)? I ended up answering my own question a bit through this article (https://journals.ashs.org/downloadpdf/journals/horttech/9/4/article-p594.pdf), but maybe the procedure varies a bit in Arctostaphylos, especially since I wouldn't want to disturb the roots or introduce pathogens in that process.

It also brings up the possibility of looking at pore number in germinating pollen (germinal pores), maybe this would be useful to explore for Arctostaphylos as well?

3a) Somewhat more out of intellectual interest: Is there resistance to hybridization between ploidy in Arctostaphylos? Do hybrids have differing ploidy from their parents?

b) Does ploidy (i.e. Small-clade diploids (S2), Large-clade diploids (L2), Large-clade tetraploids (L4)) tell us anything about the evolutionary history of the various levels of Arctostaphylos? e.g. do tetraploids originate from a genome duplication even in diploids, or via hybridization in some way?

I really like the abbreviation by the way, and it seems like Chang and Parker et. al also used it in their 2020 paper you referenced in another thread.

I also wonder about what you said regarding A. crustacea vs tomentosa and needing large stems to differentiate the two. I should look through my older Arctostaphylos observations to see if they've changed ID over time, since this might be the reason I have a sort of mental block on identifying these confidently..

Anyhow, thanks for the thought-provoking post, I'd meant to comment sooner, but iNat didn't give a notification when posted, and then I got a little bogged down in all the info the last couple times I approached it!

Anotado por yerbasanta hace 4 meses

In following an open question on trichomes linked in your synopsis above, I did some digging and started thinking again that we should also consider stomata, and what the purpose of adaxial stomata might be, and how this might relate to ecological adaptation in species/subspecies (and the relationship with omnipresent and somewhat confounding environmental plasticity).

In my mind the adaxial stomata could be present to allow plants to cool off their leaves when they're out of the fog-belt, so maybe they have been selected against in most FONM observations since there's generally cool temperatures and lots of fog? Since you're much more familiar with the distribution of adaxially-stomated Arctostaphylos, it might be something you could comment on.

This paper might have some connection to the question of stomata, though it points in the opposite direction of my earlier hypothesis (e.g. more stomata for increased fog absorption): Comparative leaf water absorption between chaparral island and mainland taxa: a common garden experiment https://scholarship.claremont.edu/aliso/vol41/iss1/4/

Both mechanisms may depend on aspect, wind, and light exposure as well, and are likely complex in relationship/nature since we have such a unique climate and soil type on FONM.

This recent thesis touches on trichome length/abundance and stomatal density measurements among various chaparral plants, including Arctostaphylos, and tests hypotheses on how environment may affect both: https://escholarship.org/uc/item/5fb1501m.

Maybe you could think backwards a bit about the environment you're looking at and what species/subspecies or characteristics you'd expect at that site (e.g. a cool, fog and wind-exposed south-facing slope vs. a sheltered, warmer low spot) to see whether you could pick out some patterns or generate a predictive model for species on FONM or elsewhere.

I'm beginning to sense you might want to break this post up into various aspects at some point.

Anotado por yerbasanta hace 4 meses

Great ideas / questions / comments. Thanks! I'll digest and reply / update...

Anotado por fredwatson hace 4 meses

Yeah, sorry for the number of arguments and length of text, it just sort of happens with me sometimes when I get interested in a topic!

Anotado por yerbasanta hace 3 meses

Thanks for linking this to me! A fascinating read, really impressive work. I wonder why we ascribe so much taxonomic importance to bark character when it seems so variable across the ranges of some species/subspecies. It makes me think about what the potential external factors might be that select for persistent bark over "classic" red exfoliating bark.

Anotado por alex_wentworth hace 3 meses

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