The autumnal flavor designed to resemble the spices in freshly baked pumpkin pie (but doesn’t contain any actual pumpkin).
Pumpkin spice does not contain pumpkin. It’s a blend of cinnamon, ginger, allspice, nutmeg, and clove used as an ingredient to spice up pumpkin pies. This spice mix (or variations of it) goes back as far as colonial America. Unlike the spice blend you buy in the store however, most commercially produced pumpkin spice flavored products don’t contain these spices. Commercial pumpkin spice flavor uses chemicals to simulate these spices which replicates the taste of a freshly baked pumpkin pie.
One reason a synthetic flavor is used, in a latte for example, is that using the actual spices makes it taste a bit more like Indian masala tea (chai tea) instead of pumpkin pie. This synthesized flavor has been engineered to taste like the spices after they have been transformed by the pie baking process. Other reasons for using a synthetic flavor are reliability (the flavor is the same every time) and cost (synthetic flavoring is a lot cheaper than using actual spices).
He who controls the spice controls the universe
The craze for all things pumpkin spice began in 2003 with the limited release of Starbucks’ latest seasonal specialty drink, the Pumpkin Spice Latte (PSL). With the success of their winter themed Peppermint Mocha and Eggnog Latte, Starbucks wanted an autumnal offering. Inspired by the flavors of freshly baked pumpkin pie the marketing team chose the name Pumpkin Spice Latte despite the drink not containing any actual pumpkin.
In 2004 the drink was offered nationwide and became the most popular seasonal Starbucks beverage, generating an estimated $1.4 billion in sales as of 2017. It also started the flavor trend of all things getting a limited edition pumpkin spice variety. You can find candles, lip balm, cereal, soap, SPAM, chocolate candy, air fresheners, beer, and more all with pumpkin spice flavors.
Added info: Starting in 2015 the Starbucks PSL now contains some amount of pumpkin, but the flavor of the drink is still created using a pumpkin spice flavoring. Also, despite the autumnal seasonality of the drink, the PSL is on the Starbucks Secret Menu and you can buy it all year round.