i894 A TEXTBOOK OF THEORETICAL BOTANY 



cosmopolitan species, possesses racemose inflorescences. It is sometimes 

 cultivated in gardens. Species of Ceratostigma (Fig. 1809) are also culti- 

 vated for their fine blue flowers. There are ten species, found in China 

 and Japan, which possess compound racemose inflorescences. 



BORAGINALES 



In an attempt to split the order Tubiflorae into a number of smaller 

 groups Hutchinson has suggested the introduction of a number of separate 

 orders of which the Boraginales is one. In this work we have not thought it 

 advisable to go as far as Hutchinson, more especially because it would be 

 necessary to consider a number of relatively unimportant families if a clear 

 idea of Hutchinson's method was to be given. We have, however, retained 

 Hutchinson's order names as far as possible and will discuss the following 

 four orders, Boraginales, Solanales, Personales and Lamiales, all of which 

 were included by Engler in the Tubiflorae. While it is desirable to divide 

 the Tubiflorae into smaller groups it is important to appreciate that the four 

 orders are closely related and are thought to have a common origin from 

 regular, isostemonous flowers in which there has been an increasing 

 tendency towards the development of zygomorphy. 



In the Boraginales the corolla is actinomorphic, but a more interesting 

 feature is the reduction and specialization of the gynoecium, in which the 

 ovary, which was originally bilocular, becomes divided by a false septum 

 into four uniovular segments. In the Solanales, the flowers are regularly 

 isostemonous, with a bilocular multi-ovulate ovary; while in Personales and 

 Lamiales the corolla shows marked zygomorphy, with a reduction in the 

 number of ovules in the Lamiales but a multi-ovulate ovary in the Per- 

 sonales. 



We may define the Boraginales as Metachlamydeae in which the 

 plants are mostly herbaceous, or rarely woody, with an actinomorphic 

 corolla and epipetalous stamens which alternate with the corolla lobes. 

 The ovary is bicarpellary, often deeply lobed, with a gynobasic style and 

 paired ascending ovules. 



As recognized by Hutchinson this order does not include the families 

 Polemoniaceae or Hydrophyllaceae which he separates into a distinct order, 

 the Polemoniales. This differs mainly in the numerous sessile ovules and 

 in the axile placentation. The Polemoniaceae are a small family occurring 

 mainly in the New World and consists of about 300 species. They are 

 mostly annual or perennial herbs or occasionally climbers. Among common 

 garden plants belonging to the family we may mention Phlox (Fig. 1810), 

 various species of which are common in gardens, Polemonium which is 

 also grown as a herbaceous garden plant and Cobaea scandens (Fig. 181 1) 

 which is a greenhouse tendril-climber, often planted out during the 

 summer. The flowers are protandrous, greenish at first with an unpleasant 

 smell and adapted to fly-pollination. Later they become purple with a sweet, 

 honey scent and are pollinated by bees. 



