Yep, they are short lived especially in the humid southeast due to canker problems when they reach 15 to 25 years old. In climates with low summer humidity they can live over 100 years. Lombardy Poplars do have brittle twigs, and when the top dies they will keep sending up suckers and new shoots from the stump. A much longer lived and nicer kind is Theves Poplar, it's almost exactly like Lombardy but is much more suited to high humidity and probably could live 80+ years. Populus is my most favorite genus of trees, I think all poplars are very beautiful with their glossy fluttering leaves and the nice surf sound they make in the wind.

No longer a very highly recommended cultivar :-) In addition to the root suckering noticed by the OP and common to most members of the genus, it possesses weak wood prone to breakage and wind and winter damage and is commonly affected by a canker that halts growth and can limit lifespan. As one source describes it: "grows fast and dies young" :-) Here is a link that might be useful: interesting article on Lombardy poplar

It is sending up sucker growth because it looks as if the main leader died. Things happen. Cut out the dead leaders and prune back what you don't want in the fall.

Resin is right that there is no consensus in the literature. The best treatment of the subject was done by S. Bugala - a Polish dendrologist and poplar expert. He argues that 'Thevestina' is really a cultivar of P. usbekistanica (an eastern P. nigra relative) and should really be called 'Afghanica'. This refers to a clone that is extensively grown throuhout southeastern Europe, North Africa, the Middle east and Mediterranean. It is either female - or hermaphroditic, fastigiate in form, has white bark and leaves that are longer than wide. Also, it can be distinguished from 'Italica' by its cylindrical stem (buttressed in 'Italica'), lack of burs and epicormic shoots that are typical of 'Italica'. See the pics below.... Although there is one clone that is widespread and was thought to have been distributed by the Turks and Arabs via the Silk Road, in reality there are several clones - some male and female. In Turkey, it is treated as a variety (P. usbekistanica var. afghanica). Specific cultivars have been selected in Iran, Romania and Iraq as well. Here in the U.S. is a different story althogether. Although the true 'Afghanica' is found in Seattle and possibly elsewhere, the clone that is sold as 'Thevestina'/'Afghanica' is mislabeled. It is in fact, 'Plantierensis'. This clone is a cross between the western European P. nigra var. betulifolia and 'Italica' (several clones were selected by the Simon-Louis Nursery at Plantiers, France in the 1800s, so 'Plantierensis' really applies to several clones - a male is predominant). It is characterized by a very leafy and slightly broader crown (than 'Italica'). It also has slightly pubescent new leaf petioles (inherited from var. betulifolia). I have never seen the true 'Afghanica' sold in the U.S. and according to a friend in Holland, this same situation occurs in Europe. I have propagated from the Seattle trees and also have several other clones from Turkey. They are very promising for warmer areas (I'm in north Florida). This spring I also raised about 300 seedlings from seed from the Seattle trees. I don't know if they are hermaphroditic and the seedlings could be 'Afghanica' x 'Italica', 'Afghanica' x 'trichocarpa or something else. I will select out the best, disease-free seedlings for further testing. here is a photo showing the difference in leaves between 'Afghanica' and 'Plantierensis' http://i234.photobucket.com/albums/ee306/smit1278/P1080833.jpg here is a photo of the trunk of an old 'Afghanica' http://i234.photobucket.com/albums/ee306/smit1278/P1040771.jpg here is another one http://i234.photobucket.com/albums/ee306/smit1278/oldAfghanicabark2.jpg here is a photo of the trunk of an old 'Italica' (or 'Plantierensis) for comparsion http://i234.photobucket.com/albums/ee306/smit1278/P1040703.jpg here is a clone selected in Turkey http://i234.photobucket.com/albums/ee306/smit1278/Gazi.jpg here is another old 'Afghanica' in Seattle http://i234.photobucket.com/albums/ee306/smit1278/P1050027.jpg