The predominant function of thorns, spines and prickles is deterring herbivory in a mechanical form. Not all functions of spines or glochids are limited to defence from physical attacks by herbivores and other animals.echnically speaking, many plants commonly thought of as having thorns or spines actually have prickles. Roses, for instance, have prickles. Other structures that look alike are spinose teeth, spinose apical process, stiff trichomes and stinging trichomes.
1 This will help the sirloin cook from all angles and sear in the juices.  Grill the steak with lid down for 4-5 minutes depending on thickness. When grilling steaks, you need to resist the urge to open the lid and look.
For medium-rare, cook the steak until the internal temperature is 135 degrees, then remove and allow the top sirloin steak to rest for 5 minutes. Use a good pair of tongs to flip the steak about half way through the cooking time. Once it is done, let it rest on the plate for 5 minutes before you cut into it.This lets the juices redistribute and keeps them from running out all over your plate. Serve up that perfectly grilled top sirloin steak and enjoy! melt the butter in the microwave. After the butter is melted, I add minced garlic (I actually use a garlic press) Brush the butter mixture onto one side of the steak. Make sure you get lots of garlic on there since the wife is out anyway. Lay the top sirloin steak onto the grill, butter side down.