the above is for **piante coltivate in zolla**

explanation links:
http://www.wisegeek.com/what-is-a-root-ball.htm

http://www.hedgesdirect.co.uk/acatalog/Potted_v_bare_root_v_...
Root Balled Hedging Plants


Bare root (or whips), cell grown, P9's pot grown and rootballed

Many evergreen plants are sold as root balled, particularly large plants. They are grown naturally in a field (often for many years) and when ready for delivery, they are scooped out of the ground by a machine, which cuts a ball around the root which is then wrapped in a biodegradable hessian sack or a wire contraption (for the larger plants), both of which are left on the plant when planted and both decompose naturally.

Root balled evergreens are cheaper than pot grown evergreens (due to the lower cost involved in this growing method) - and particularly when customers are looking for tall, bushy plants, this is a very economical way to establish a new hedge. We do not grow these plants ourselves - they come from Holland where there are specialists - and we have chosen a grower who grows absolutely top quality plants. We take a very thin margin on these plants so that we remain competitive……………
Sometimes, root balls (particularly those over 1.5m) can defoliate or suffer from yellowing leaves when the first hot weather arrives in the first season after planting - this is just the plant being shocked by the heat and it merely needs plenty of water to help it to recover.

http://eur-lex.europa.eu/Notice.do?mode=dbl&lng1=en,it&lng2=...

Forest trees This subheading includes young plants from seeds of coniferous or deciduous trees normally used for afforestation. They are generally supplied without **balled roots**

da bosco Rientrano in questa sottovoce i piantimi ottenuti da semi di conifere o di latifoglie abitualmente utilizzati per il rimboschimento. Essi sono in genere forniti senza la ** zolla di terra**. |

http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees...
Plants can be purchased as bare-root, ball and burlapped (B&B), or as container-grown plants. Planting procedure varies somewhat with each type.