B. swaseyi bud scale series (leftmost is oldest).

B. trifoliolata bud scale series (leftmost is oldest).
(Click for larger images.)

Cataphylls of Berberis in Northern Hays County

Cataphyll (bud scale) morphology provides a number of features that distinguish our two species and also support the hybrid status of plants identified as such on other criteria. Cataphyll persistence, however, does not distinguish our species - both B. swaseyi and B. trifoliolata (as well as hybrids) have strongly persistent bud scales. (For a discussion of Berberis bud scale persistence.)

As rudimentary leaves our Berberis cataphylls closely parallel the stipulate petiole leaf base. The most prominent shared features, although reduced, are a broad sheathing base (the scale) with one or more long slender lateral teeth (the 'stipule'), a central terete projection (the petiole-stem) with an annular abscission zone near its tip (the rachis node for the proximal leaflets) - referred to here as a 'peg'. The above illustrations shows this for our three types. To get a clear sense of the cataphyll form, freshly matured specimens from a recent bud must be used, since the dry flagelliform teeth and peg tip often break off. For comparison, petiole bases of hybrids and B. trifoliolata are show below.

Petiole bases: hybrid (left); B. trifoliolata (right).

B. trifoliolata: Bud scales (left); Petiole base (right).

Loss of the mucronate central tip leaves the blunt peg similar to the result of normal rachis abscission; shown below for B. trifoliolata (abaxial (left) and adaxial views).

Comparison of cataphyll measurements

The bud scales of B. trifoliolata are consistently smaller and provided with relatively more prominent appendages (teeth, pegs) than B. swaseyi. Hybrids tend to be closer to one or the other species – as shown in the outlines at the top of the page, resulting in overlapping ranges and intermediate averages for scale length, although these often seem to have even longer teeth and larger pegs than B. trifoliolata.

B. swaseyi	scale length	max. tooth length	peg length	peg width	total length
average	2.7	0.1	0.2	0.2	2.9
range	1.9 - 3.7 mm	(0.1)* - 0.28 mm	(0.09)* - 0.5 mm	0 - 0.6 mm	2 - 3.8 mm
B. trifoliolata
average	1.4 mm	0.5 mm	0.6 mm	0.3 mm	1.8 mm
range	0.8 - 2.6 mm	(0.1)* - 0.9 mm	0.1 - 1.1 mm	0.18 - 0.5 mm	1 - 2.8 mm
B. swaseyi X        B. trifoliolata
average	1.6 mm	0.7 mm	0.8 mm	0.4 mm	2.2 mm
range	1 - 2.2 mm	(0.1)* -1.5 mm	0.4 - 1.4 mm	(0.3)* - 0.6 mm	1.7 - 2.7 mm

*teeth & pegs were not always present

My results don't closely match those give by Whittemore (FNA) for our two species:

B. trifoliolata: "Bud scales 2-3 mm, deciduous."
B. swaseyi: "Bud scales 1.5-4 mm, deciduous."