Crataegus rhodamae-loveae, Dickinson & Han, 2023

KEY TO WESTERN NORTH AMERICAN CRATAEGUS SER. DOUGLASIANAE WITH CONSISTENTLY (15–)20

STAMENS PER FLOWER (OR FRUIT). 1. Short shoot leaves densely toothed,8–12 teeth per Cm adjaCent to leaf apex (pollen-infertile allotriploids and allotetraploids; British Columbia, Idaho, Montana, Oregon and Washington east of the CasCade Range). __________ C. suksdorfii (Sarg.)

KrusChke sensu striCto. 1. Short shoot leaves more Coarsely toothed,6–9 teeth per Cm adjaCent to leaf apex. 2. Thorns 2.5–4 mm in diameter at base;petioles 1–2.5 mm (pollen infertile autotriploids;Marin and Sonoma Counties, California)._____________________________________________________________________________ C.gaylussacia A.Heller. View in CoL 2. Thorns 1.5–3 mm in diameter at base;petioles 11–14 mm (mostly pollen-fertile diploids;northern California, Oregon, southwestern Washington,west of the CasCade Range).____________________________________ C. rhodamae-loveae View in CoL sp.nov.

Crataegus × suksdorfii (Sarg.) Kruschke, Milwaukee Public Mus. Publ. Bot. View in CoL 3:163. 1965 (as sucksdorfii) ( Fig. 8A View FIG ). TYPE: U.S.A. WASHINGTON. Klickitat Co.: “Falcon Valley,” 10 Aug 1905, W. N. Suksdorf 4419 (HOLOTYPE designated here: HUH00018057 !, Fig.9B View FIG ; Table 2; ISOTYPES: HUH!, WS!, WTU! Note.— Holotype not designated by Kruschke.

≡ Crataegus douglasii Lindl. var. suksdorfii Sarg. Bot. Gaz. View in CoL 44:65. Jul 1907; SYNTYPES: W. N. Suksdorf 4034 ( CAS!, HUH!, ID!, MO!, ORE!, OSC!, WS!, WTU!); 5026, ( DAO!, HUH!, WS!);5031, ( HUH!, WS!); 5040, ( HUH!, WS!),all from Bingen , Washington, U.S. A ( Table 2). Holotype not designated; W. N. Suksdorf 4419 incorrectly cited as “4919” by Sargent .

= Crataegus punctata Jacq.var. brevispina Douglas ex Hook. (K!) ( Fig.10 View FIG ).

Description.— Trees or shrubs to 7(–12) m, bark orange-brown on young twigs, becoming gray with age, smooth, but on trunks and large branches flaking irregularly. Thorns 7.5–14 mm long, more or less straight, 2.5–3.5 mm in diameter at the base. Leaves (microphylls–) notophylls, unlobed (occasionally pinnately lobed), singly to doubly serrate, 9–11 teeth per cm adjacent leaf apex, leaf base angles acute, bases cuneate or decurrent, apex angles obtuse to acute, apices mostly convex or straight, surfaces pubescent, glabrescent, or glabrous, petioles 7–13 mm long. Flowers with calyx lobes 1–2 mm long, not toothed, stamens 15–20, free, undehisced anthers pink at anthesis, 4–5 styles. Dried fruits 4–7 mm in diameter, purple-black at maturity, with persistent calyx lobes. For exemplars, see https://morphobank.org/permalink/?F1091.

Distribution.— As circumscribed below, western North America (southernmost Alaska, British Columbia, Oregon and Washington east of the Cascades, Idaho, western Montana.

Remarks.— We denote this taxon as a nothospecies because molecular evidence indicates that it is an allopolyploid intersubgeneric hybrid, formed as a result of a series of crosses and backcrosses involving fertilizations of unreduced gametes in one or more members of C. subg. Americanae and ancestral, diploid C. suksdorfii sensu lato (C. subg. Sanguineae ) ( Fig. 7 View FIG ; Liston et al. 2021; Lo et al. 2009b; Lo et al. 2010; Zarrei et al. 2014). In this connection, we note that the feature linking the type material to the wider sample of allopolyploid C. suksdorfii sensu lato available to us is the reduced stainability of pollen, contrasted with the greater stainability of pollen from diploids and tetraploids ( Fig. 6 View FIG ). The original material for Sargent’s description of his new variety named in honor of the collector, W.N. Suksdorf, comprises specimens from five trees, four along the banks of the Columbia River in Bingen, Washington, and the fifth from Suksdorf’s farm, collected from “Border of meadow, Falcon Valley, W. Klickitat Co,” approximately 10 km southeast of Glenwood and 535 m above Bingen (Township 5N Range 11E Section 12, east half of the northeast quarter; Love 1998; Weber 1942; Weber 1944). These five trees are the only materials of this taxon cited in Sargent’s protologue. There is no reference to a type in the paper or on the labels of the specimens cited, unusual even in light of Sargent’s idiosyncratic use of type designations ( Macklin et al. 2000). Accordingly, we designate the Falcon Valley specimen, W.N. Suksdorf’s number 4419 (HUH00018057; Fig. 9 View FIG ), collected 10 August 1905 (the right hand gathering of the two on the sheet) as the holotype for C. suksdorfii (Sarg.) Kruschke because overall, it is the specimen most typical of allopolyploid C. suksdorfii sensu lato. This collecting site is close to, and at an elevation (560 m above sea level; ASL) comparable to (i.e.,> 100 m ASL), that of most of the other locations at which we have found allotriploid and allotetraploid individuals of this species ( Fig. 3 View FIG ; Dickinson et al. 2021). Sea level or near sea level occurrences of this taxon are found at northern coastal sites in Alaska, British Columbia, and Washington (e.g., Hyder, Haida Gwaii, San Juan Is.; Appendix 1). A holotype is needed because Kruschke’s change in rank was not validly published, as he failed to realize that after 1 January 1958 for his change in rank to be validly published he needed to designate a single specimen as the type of the new name ( Phipps 2008; Shenzhen Code Article 8.1, 8.2, and 40.1; Voss 1965). We nevertheless retain Kruschke as the authority for the change in status as Phipps has done in other cases ( Phipps 2008).

Ploidy level.— Allopolyploids, 2n = 51 and 68, based on flow cytometric determinations of nuclear DNA content (N. Talent unpubl. data; Coughlan et al. 2014; Lo et al. 2013), and analyses of nuclear and plastome DNA sequences ( Liston et al. 2021; Lo et al. 2009b; Lo et al. 2010; Zarrei et al. 2014).

Similar species.— Crataegus shuswapensis J.B. Phipps & O’Kennon may have 15–18 stamens per flower but typically has flowers with 10 stamens; leaves are rhombic and broader and more markedly lobed than is typical in C. × suksdorfii . Crataegus shuswapensis is known only from south-central British Columbia ( Phipps & O’Kennon 2002; for exemplars, see https://morphobank.org/permalink/?F1098).