What’s a dichotomous key? Help

Taxus

The report of Taxus ×‌media Rehd. in RI (Tucker 2006) was based on a hybrid with Taxus umbraculifera (Sieb. ex Endl.) Ravencroft var. hicksii (hort. ex Rehd.) Spjut as the seed parent and possibly Taxus biternata Spjut as the pollen parent (i.e., the second parent is not confidently known). The specimen shows leaves arranged in 4 or more ranks and radiating in ± all directions on the young shoots (as in T. umbraculifera). Taxus cuspidata, with which this plant shares some similarities, such as abruptly bent petioles and many rows of stomates, has leaves arranged in only 2 ranks (as to the attachment of the petioles), but the blades all ascending to erect. Reference: Spjut (2007).

Choose this species
T. baccata
1a. Winter bud scales blunt at the apex, slightly keeled; leaf blades gradually tapering to  the apex [Fig. 49]
See list of 2 species in 1b
CHOOSE THIS LEAD
1b. Winter bud scales sharply pointed to cuspidate, definitely keeled or folded; leaf blades abruptly tapering to the apex [Fig. 49]
- Choose this species
  T. canadensis
  2a. Low shrubs with straggling, diffusely branched habit; leaf blades 1–2 (–2.4) mm wide; stomates in 5–7 (–9) rows in each band; petioles gradually curved or with an abrupt bend near the junction of the branch, not clasping the branchlet; seeds round or somewhat compressed near apex, but not angled
- Choose this species
  T. cuspidata
  2b. Plants upright; leaf blades 2–3 mm wide; stomates in (7–) 9–14 (–19) rows in each  band; petioles with an abrupt bend near the junction of the blade, clasping the branchlet; seeds 4- or 5-angled near apex

Show All Couplets

Show photos of: Each photo represents one species in this genus.