Compared to say, moving the Earth into a diffenent orbit perhaps. But in the state I like to call “reality” it would be well beyond current engineering capabilities and material strength.
Solar escape velocity is about 42 km/s at Earth’s orbit. Since the Earth has an average orbital speed of about 29.8km/s you’d have a hell of a lot of extra speed to make up.
Assuming our hosepipe is fixed in rotation and you’re not adding any extra energy to the water, you’d have to be at least geostationary orbit (~35.8*10[sup]3[/sup] km) before it wouldn’t automatically fall back down on the Earth. If you are going to give it extra speed at the end, you’re going to need to add about 6.5km/s. Either way, the pressure required to sustain a free-standing column of water is going to cause cavitation–that is, the force holding up the water and the attraction of gravity pulling down on the water is going to make an internal pressure so low that the water will become vapor and the column will collapse.
The actual mechanic of transpirational pull alone doesn’t draw up water to the branches and leaves in a tall tree; as previously mentioned, there is also the capillary action in the xylum and the fact that, in trees, the water is in a thicker, more viscious colloid which helps suspend it. Fundamentally you can’t consider the xylem to be just a tube with a continuous stream of water suspended and motivated strictly by a pressure differential; it’s more like a sponge, such that when the upper part “dries out” from water being transported to leaves it draws the fluid below it, and so forth, moving more like a series of rocket climbers ascending a chimney than a stream flowing upward. On that basis there is no limit to the height water can be drawn up by such a mechanism because any given section is already self-supporting. A tree just isn’t a good analogue to a hosepipe.
I’m no expert on trees but I would guess that the maximum height of a tree depends on the structural strength of the tree in resisting wind or ice loads and the size of the root ball in terms of both anchoring it too the ground and absorbing enough water to support growth. I doubt that the ability to transport water has any limitation on height.
Regarding the debate over osmosis (and without entering into any of the vituperation), while osmosis–the movement of water across a permeable membrane via a difference in concentrations of ions in solution–is critical to allowing the roots to absorb water, it plays no role in transporting water up the trunk and to the leaves and other living parts of the trees, and indeed, osmotic pressure differences are dramatically smaller than what would be necessary to lift water more than a few inches. Osmosis just isn’t a mechanism by which the overall process of transpiration moves water from the roots to the leaves in trees.
Stranger
Getting the water into the roots is IMHO a rather critical start of the whole Transport process. But that’s just IMHO. I could be wrong.
Don’t worry: if you are right, then you can destroy me by facts, anger isn’t nessesary. In fact- *Please *destroy me with facts, that fights ignorance. Cool cites by the way, thanks! 
“Ah, the irony! It burns!” 
On the desert the effect of water can be quite spectacullar. Below a conyon not far from here you walk through greasewood (creosote)bushes (which, as you said, might possibly be even older than the bristlecomes) that are 4’ to 5’ tall. In one step you go into bushes 10’ to 12’ tall. You can easily trace the path of an underground stream down the alluvial fan.