  Inspired by the infinite families of finite and affine root systems, we
consider a "stretching" operation on general crystallographic root systems
which, on the level of Coxeter diagrams, replaces a vertex with a path of
unlabeled edges. We embed a root system into its stretched versions using a
similar operation on individual roots. For a fixed root, we study the growth of
two associated structures as we lengthen the stretched path: the downset in the
root poset (in the sense of Bj\"orner and Brenti [3]) and the arrangement of
shards, introduced by Nathan Reading. We show that both eventually admit a
uniform description, and deduce enumerative consequences: the size of the
downset is eventually a polynomial, and the number of shards grows
exponentially.
