1f. Taxus baccata var. jacksonii (Paul) Gordon, Pinet. Suppl. 99 (1862).  Taxus. baccata jacksonii Paul, J. Hort. Soc. Lond. 493 (1861).  Developed by William Paul in Cheshunt, England; origin of material unknown; original herbarium material unknown.  Neotype Proposed—Sweden. Blekinge, Sjuhala—Holmgren, 6 Aug. 1925 at US! (US: 1276222; leaves with 8 stomata rows/band, abaxial marginal region lacking papillae across 5 rectangular cells, papillose across midrib, papillae medial).

Jackson yew. Distribution: Euro-Mediterranean.

Appearing to be trees with horizontal branches bearing long subpinnate branchlets, or occasionally with short branchlets, the branchlets pendulous or horizontal, often with a bright reddish orange tint; bud-scales conspicuous at base of branchlets, adpressed, deltoid, thickened medially but not conspicuously nerved, obtuse; leaves mostly spreading along two sides of straight horizontal branchlets, becoming erect on recurved or pendulous branchlets, overlapping slightly, especially near apex of branchlets, linear, falcate, obtuse to acute, 1.7–2.5 cm long, 1.5–2.5 mm wide, pale olive green above and pale yellowish orange below in herbarium specimens, plane to abruptly folded along margins; male cones reflexed, scattered on young branchlets, maturing just below apex; seeds usually maturing on 2 ^nd yr or older branchlets, occasionally on 1^st yr branchlets, subcylindric to subglobose, orange to reddish brown.

The Jackson yew is recognized by the relatively straight horizontal branches with long subpinnately arranged branchlets from which leaves spread widely along two sides (two-ranked).  The leaf blades along the uppermost part of branchlets scarcely overlap the branchlets at their base in pressed specimens.  The dried adaxial leaf surfaces  appear pale olive green in color and are strongly convex.  Additionally, branches in many specimens are notably orange in color, as also seen on the abaxial leaf surface. Taxus baccata var. jacksonii is similar to T. baccata var. variegata in branching, but the branches differ in their appearance of being less rigid with fewer erect leaves.

The Jackson yew is also similar to T. cuspidata in the adaxial surface of leaves appearing rugose (dried specimens), and occasionally in other features such as leaves spreading upwards, leaves lacking papillae across more than 8 marginal cells, and seed on 2nd year or older growth.   Taxus cuspidata is recognized, however, by leaves bending more abruptly near petiole, and by the cuspidate scales at base of branchlets, in contrast to the smaller obtuse scales of var. jacksonii.

Representative Specimens—Spain/France: Pyrenees centr., montis Port de Bensque, Endrels Aug 1831 (K, S); ex Herb. Hook., 1867 (K); Batsmanshus Paroeciae Elfkarl, Rosalagiae abundans, Lagerheim & Sjogren, Jul 1844 (K).  Switzerland: ex Herb. A. Gray (K). Austria: Tirol, Greolen (PH).  Hungary: 445 m, Schönach 3084 (S: C-2061A; US, top left specimen of two); Vorarlbergia, 445 m, Wagriesh (US: 481917).  Finland: Alandia, par. Lemland, in insula Jungfruskár, Vidlund, Finlandee Exsic. 419 (K, p.p., upper specimens). Syria: Düldül, Mt. Amanos, 1500–2000 m, Haradjan 3865 (S).  Representative photos: Jardín  botánico  Mundani, http://jardin-mundani.info/taxaceae/teixC.jpg

Hungary: Left Photo: An herbarium sheet at Stockholm (S) with two specimens, T. baccata var. jacksonii on left, T. canadensis var. canadensis on right.  Close-up photo is of var. jacksonii.  Flora Exsiccata
Austro-Hungarica 3084, Schönach.  Illustration from leaf of specimen on left indicates abaxial leaf margin lacks papillae across 4 cells, followed by 14 rows of papillose cells, then a stomata band with 10 stomata rows, and finally by a papillose midrib.

Hungary: Left Photo: An herbarium sheet at the Smithsonian Institution (US) with two specimens, T. baccata var. jacksonii on left, T. canadensis var. canadensis on right.  Close-up photo is of var. jacksonii.  Flora Exsiccata
Austro-Hungarica 3084, Schönach.  Illustration from leaf of specimen on left indicates abaxial leaf margin lacks papillae across 4–5 cells, followed by 10 rows of papillose cells, then a stomata band with 8 stomata rows, noted to be olivaceous in color and finally by a papillose midrib of 21 cells across.   A separate x-section of the leaf was noted to have epidermal cells 8–10 µm tall on both the abaxial and adaxial leaf surfaces, and the width was noted to be 20–25 µm on adaxial surface and ~20 µm on the abaxial surface.

Hungary: Left Photo: An herbarium sheet at the Museum of Natural History in London (BM) with three specimens, T. baccata var. jacksonii on right and at bottom, T. canadensis var. canadensis on upper left.  Flora Exsiccata Austro-Hungarica 3084, Schönach. Close-up photo shows both upper specimens, the male cones belong to var. jacksonii.  Differences in these specimens can be seen by the channeled adaxial leaf surface along the midrib of T. canadensis, whereas the adaxial leaf surface of T. baccata var. jacksonii has a raised midrib, a rather significant difference between the two specimens.  The collection and distribution of these specimens would seem to be intended to show variation in the yew for the region.

Hungary: Wagriesh (US: 481917).  Illustration from leaf of specimen indicates abaxial leaf margin lacks papillae across 3 cells, followed by 8 rows of papillose cells, a stomata band with 8 stomata rows, and a partially papillose midrib of 15 cells, the papillae rather obscure, appearing only on the outer 7 rows of cells.

Finland: Alandia, par. Lemland, in insula Jungfruskár, Vidlund, Finlandee Exsic. 419 (K, p.p., upper specimens).  The bottom specimen, not studied in detail, is T. baccata var. glauca, as recognized by the recurved branchlets and upward secund leaves.  Illustration from leaf of specimen indicates abaxial leaf margin lacks papillae across 4 cells, followed by 9 rows of papillose cells, a stomata band with 8 stomata rows and one additional row noted to occur on the midrib, and a papillose midrib of 10 cells, the papillae rather prominent and marginal in position.  Large spherical parenchyma cells were also noted in the leaf mesophyll, a feature that is similar to T. contorta.

Sweden, Blekinge, Sjuhala—Holmgren, 6 Aug. 1925 at US: 1276222.  Illustration indicates leaves have 8 stomata rows per band, an abaxial margin that lacks papillae across 5 rectangular cells, followed by 7 rows of papillose cells, and a midrib that is entirely papillose, the papillae ±medial.  Proposed neotype.

Spain/France: Pyrenees centr., montis Port de Bensque, Endrels Aug 1831 (S).  Illustration from leaf of specimen indicates abaxial leaf margin lacks papillae across 5 cells, followed by 9 rows of papillose cells, a stomata band with 8 stomata rows, and a midrib lacking papillae (smooth).

Syria: Düldül, Mt. Amanos, 1500–2000 m, Haradjan 3865 (S).  Illustration from leaf of specimen indicates abaxial leaf margin lacks papillae across 8–10 cells, followed by 8 rows of papillose cells, a stomata band with 10 stomata rows, and a midrib of 14 cells across, all lacking papillae (smooth).  The vascular bundle was also noted to react by turning red from an application of a solution of p-phenylenediamine in 95% ethyl-alcohol.

Switzerland: ex Herb. A. Gray (K). Illustration from leaf of specimen indicates abaxial leaf margin lacks papillae across 5 marginal cells, and nearly so on another 4 rows of cells, followed by 8 rows of papillose cells, a stomata band with 9 stomata rows, and a midrib of 15 cells across, all lacking papillae (smooth).