A Gardening Journal

Today in the Garden of a Lifetime: The Hardy Orange, Fruit and Thorn

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If you're not armed with sharp pruners and a zen mindset, the thorns of hardy orange are implacable.  For any flesh less protected than that of a tortoise, they are dangerous and invincible, so long and so rigid they could penetrate right through a palm or a foot.  From this shrub's point of view, its thorns are a triumphant strategy for preserving the plant's lebensraum.  Except, that is, for the fruit. 

 

The oranges may be small and full of pith, but they also contain seeds.  One purpose of seeds is to disperse the plant farther than it can grow.  A plant can't pull itself up by the roots and move outward to new territory and, even if it did, it's a zero-sum game:  A new plant over here would mean one fewer plant over there. 

 

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But a seed can be carried by an animal, and can re-form the entire plant even as the mother plant remains intact.  And many seeds can be produced at once, giving the potential for many additional plants.

 

But the fruits of hardy orange are only formed on growth that was produced the year before.  The growth of the current season can be several feet long, and is often the thorniest ever.  It has the potential to limit or even prohibit access to the fruits by foraging animals.  Could any bird large enough to pluck an entire fruit and carry it away have first found a safe footing on the new growth?  True, smaller birds relish hardy orange, because they can nest right in the core of the canopy.  But they're not big enough to carry the fruits away and, in any event, would only carry them further into the core of the shrub, for protected dining.  And where monkeys are indigenous, wouldn't hardy orange be another kind of "monkey puzzle tree?"  Too big a risk of injury to be worth the reward of the fruit. 

 

And then there's the matter of the fruit's poor, well, "fruitiness."  They are peel and pith.  What animal would want them?  It would take a dedicated cook to make even marmalade from them.  

 

It's not unusual to see fruits from previous years still trapped in the bush's densely twiggy interior.  And it's the norm to see fruits on the ground only directly under the bush: They can escape the maze-like growth only by way of gravity, not through the assistance of animals. 

 

The seeds of Poncirus trifoliata are reasonably successful at germination, even here at the cold end of this bush's hardiness range.  Seedlings are directly beneath the canopy of the mother, but for thorny plants, there's actually an advantage to propinquitous progeny.  Germinating in the semi-shade of the mother shrub's canopy is compensated by the protection of her vicious thorns.  And as seedlings grow into daughter shrubs, their new growth adds to the colony's overall tangle of impenetrable armor.  The increase in colony size may only be modest, but the security of the colony is enhanced relentlessly.

 

 

Here's how to grow hardy orange.  The pruning strategies I recommend in the link maximize the amount of time in each year that the bush has a tidy shape—but also mean that the best show of fruit will be every other year.  

 

 
 
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