Hollies Ilex

Of eighteen Ilex species assessed, six are rated keep away, five fire resistant, five assessed without a verdict, and two genuinely contested. The genus ranges from low shrubs to fifty-foot trees in the Aquifoliaceae family, native across the Southeastern, South-Central, Northeastern and North-Central United States, hardy from USDA zone 4a into zone 8a.

The most heavily studied member of the genus, inkberry, falls on the keep-away side with yaupon and Chinese holly. Yaupon's own assessment blames volatile oils and growth habit, a theme that recurs across a third of the genus's rated members. Inkberry's assessment notes drought sensitivity and a need for moist, acid soil; Chinese holly's assessment notes its adaptability to drought, pH and soil type. Same rating, different reasons, in the sources' own words.

On the resistant side, common winterberry and tarajo holly carry the rating on substantial assessment, and Possum-haw holly carries it on a thinner record. Two members, Ilex x meserveae hybrids and topel holly, are genuinely contested rather than settled. The rest have been assessed without any source taking a side, and unrated is not the same as safe.

None of this settles the genus; one species outside the split makes the point plainly. The Forest Service's 1991 review of American holly found its bark thin enough that light fire can kill even large trees in the understory, a vulnerability recorded for that species, not a trait shared across the genus. A holly by the house is a single-species question, and the family name will not carry the answer alone.